The value of the column c2 or c3 needs not to be unique. This option is available in Postgres 11 and later. -- CREATE UNIQUE INDEX ON "accounts" ("owner", "currency"); ALTER TABLE "accounts" ADD CONSTRAINT "owner_currency_key" UNIQUE ("owner", "currency"); Enter fullscreen mode Exit fullscreen mode The preferred way to add a unique constraint to a table is ALTER TABLE ADD CONSTRAINT. May 19, 2015 · Adding UNIQUE constraints to tables in Postgres is very easy! Imagine we have the following table: CREATE TABLE users ( id uuid PRIMARY KEY NOT NULL DEFAULT uuid_generate_v4(), email text ); If we want to ensure that each user has a unique email we simply add: ALTER TABLE users ADD CONSTRAINT email_unique UNIQUE (email); To add a (multicolumn) unique constraint to a table: ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode); To add an automatically named primary key constraint to a table, noting that a table can only ever have one primary key: ALTER TABLE distributors ADD PRIMARY KEY (dist_id); 1. 在 PostgreSQL 中,ALTER TABLE 命令用于添加,修改,删除一张已经存在表的列。 另外你也可以用 ALTER TABLE 命令添加和删除约束。 语法. The column-definition is the data type of the new column. 26 Feb 2020 The PostgreSQL ALTER TABLE statement is used to change the If we want to add a unique constraint item_vendor_ukey in orders table the  UNIQUE(column_list);. The Value of the column must be unique across the whole table. Now run the SQL  1 Aug 2017 create table demo as select generate_series n from generate_series(1,2); SELECT 2 alter table demo add constraint demo_pk primary key(n);  DROP CONSTRAINT IF EXISTS, The sql statement 'ALTER TABLE <table Can I add a UNIQUE constraint to a PostgreSQL table, after it's , psql 's inline help:  2014년 3월 28일 CONSTRAINTS 제약명 UNIQUE (컬럼2, 컬럼3));. On the Table Designer menu, click Indexes/Keys. See full list on medium. Mar 21, 2017 · Our desire is to place a UNIQUE constraint on the nullable_value that would also distinguish between NULL values. Aug 16, 2019 · For that, we drop the original constraint, and add a new unique constraint that uses our new index. ALTER TABLE distributors DROP CONSTRAINT zipchk , ADD CONSTRAINT zipchk CHECK (length (zipcode) = 6); ALTER CONSTRAINT in Postgres 9. Use the Name field to add a descriptive name for the unique constraint. e. We don’t have to rename the index this time as Postgres automatically renames it to the name of the constraint. How to add unique key constraint to an existing table. ① UNIQUE는 해당테이블에 있어서 존재하는 값이 유일해야 합니다. Feb 26, 2020 · ALTER TABLE. . A constraint can be added at the table level. Various usages of uniqueness constraintsUNIQUE use. constraint_name and nsp. The UNIQUE constraint ensures that all values in a column are different. A unique constraint is a single field  Additional restrictions apply when unique or primary key constraints are added to partitioned tables; see CREATE TABLE. Jan 26, 2017 · I just finished researching this. The syntax for creating a unique constraint using an ALTER TABLE statement in PostgreSQL is: ALTER TABLE table_name ADD CONSTRAINT constraint_name UNIQUE (column1, column2, column_n); table_name The name of the table to modify. Let’s consider an example of how to add a unique limitation to an existing table in PostgreSQL using the ALTER TABLE operator. Apr 13, 2019 · Add and Remove Unique Constraints in PostgreSQL 04/13/2019 — 1 Min Read — In PostgreSQL Constraints are a great way to ensure that an app's data conforms to certain business rules. conrelid = cls. If you're validating nulls on the database layer as well, you're protected Mar 21, 2017 · Our desire is to place a UNIQUE constraint on the nullable_value that would also distinguish between NULL values. So not what you are looking for. 用 ALTER TABLE 在一张已存在的表上添加列的语法如下: ALTER TABLE table_name ADD column_name datatype; The SQL query to make column id of table students a PRIMARY KEY is: ALTER TABLE students. Two NULL values for a column in different rows is different and it does not violate the uniqueness of UNIQUE constraint. ALTER TABLE billings ADD CONSTRAINT billings_excl EXCLUDE USING gist  27 Sep 2018 Check Constraints; Not-Null Constraints; Unique Constraints; Primary learning => ALTER TABLE trails ADD CONSTRAINT t_check CHECK  11 May 2014 Safe PostgreSQL operations for a high volume deploys without downtime. In Object Explorer, right-click the table to which you want to add a unique constraint, and click Design. Rename existing table column. The drop constraint function allows the user to enter a constraint to drop from the table. UNIQUE (lower (MyColumn)); -- invalid syntax. Sure, you could perform this validation in your application layer, but shit happens: somebody will forget to add the validation, somebody will remove it by accident, somebody will bypass validations in a console and insert nulls, etc. public Alembic will automatically generate a stub “referenced” table and emit a second ALTER statement in order to add the constraint separately: from alembic import op from sqlalchemy import Column , INTEGER , ForeignKey op . For example, the following query adds a UNIQUE constraint for two columns: username and email. The new-column-name is the name of the new column to be added. Jan 21, 2021 · To add a new column to a PostgreSQL table, the ALTER TABLE command is used with the following syntax: ALTER TABLE table-name ADD new-column-name column-definition; The table-name is the name of the table to be modified. ALTER TABLE tablename ADD CONSTRAINT constraintname UNIQUE (columns); step 3. ) Is it only a matter of good style? To add a (multicolumn) unique constraint to a table: ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode); To add an automatically named primary key constraint to a table, noting that a table can only ever have one primary key: ALTER TABLE distributors ADD PRIMARY KEY (dist_id); ERROR: Cannot create unique index. constraint_name – The name of the unique constraint. Adding a unique constraint will automatically create a unique B step 3. tradein_clients=# SAME PROBLEM IN PGSQL 7. SELECT *. To delete a constraint, use the DROP CONSTRAINT syntax, followed by the name of the constraint you want to delete. ALTER TABLE uProfiles. However, you can have many UNIQUE constraints per table, but only one Feb 26, 2020 · The UNIQUE constraint in PostgreSQL violated when more than one row for a column or combination of columns which have been used as a unique constraint in a table. See CREATE TABLE: PostgreSQL automatically creates an index for each unique constraint and primary key constraint to enforce uniqueness. connamespace join pg_class cls on pgc. Tweet select pgc. The PostgreSQL ALTER TABLE statement is used to change the definition or structure of an existing table. add_column ( 'organization' , Column ( 'account_id' , INTEGER , ForeignKey ( 'accounts. conname; Feb 02, 2017 · Database Research & Development: Shared one demonstration to disable / enable the foreign key constraint of table in PostgreSQL. You would also use ALTER TABLE command to add and drop various constraints on an existing table. Sep 15, 2020 · ALTER TABLE racersInfo ADD CONSTRAINT uID UNIQUE (racerId); If, before adding a constraint like this, you inserted any records that would violate the condition of the new constraint, the ALTER TABLE statement will fail. column_name, pgc. We can generate a Unique constraint in PostgreSQL with the ALTER TABLE command's help, and we can also add the unique constraint using the PostgreSQL unique index. Types of constraints. However, in 9. Oct 08, 2019 · You can’t disable a foreign key constraint in Postgres, like you can do in Oracle. Drop existing table column. pl from DECLARE_UNIQUE_INDEX directives. nspname = ccu. Tweet Add unique key constraint to table. while leaving the rest of the data untou How to Remove a Not Null Constraint in PostgreSQL. conname as constraint_name, ccu. Let's look at an example of how to add a unique constraint to an existing table in Oracle using the ALTER TABLE statement. III. The constraint must be a predicate. In Postgres, currently, adding a unique index will enforce uniqueness. 만일 INSERT 또는  오라클이나 PostgreSQL 이나 pk 나 unique constraint 제약 조건을 달면 인덱스는 자동 scottdb=> alter table x add constraint xpk primary key(x);. II. ALTER TABLE large_table ADD CONSTRAINT token UNIQUE  2 May 2019 You put a unique constraint on a referenced column and you're fine. Let us create a table and alter existing columns or add new columns. consrc as definition from pg_constraint pgc join pg_namespace nsp on nsp. alter table users alter column email drop not null;. All the columns of  This PostgreSQL tutorial explains how to create, add, and drop unique constraints in PostgreSQL with syntax and examples. ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id,  alter table department add constraint unique_manager unique(manager);. Here’s a quick test case in five steps: Drop the big and little table if they exists. cellphones" Column | Type | Modifiers -----+-----+----- id When you add a UNIQUE constraint to a column or a group of columns, PostgreSQL will create a btree index on the respective column or a group of columns automatically. com PostgreSQL ALTER TABLE 命令. However, the column can have many NULL values because PostgreSQL treats each NULL value to be unique. column1, column2,… column_n – The columns that make up the unique constraint. To add a (multicolumn) unique constraint to a table: ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode); To add an automatically named primary key constraint to a table, noting that a table can only ever have one primary key: ALTER TABLE distributors ADD PRIMARY KEY (dist_id); To add a (multicolumn) unique constraint to a table: ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode); To add an automatically named primary key constraint to a table, noting that a table can only ever have one primary key: ALTER TABLE distributors ADD PRIMARY KEY (dist_id); Now, you can use ALTER TABLE statement to add the CHECK constraints to the prices_list table. CREATE TABLE Amount_list ( I. cellphones" Column | Type | Modifiers -----+-----+----- id The PostgreSQL ALTER TABLE command is used to add, delete or modify columns in an existing table. To do that, we add two unique partial indices, one for NOT NULL values and one for the NULL case on an expression using the coalesce function. Thus, it is not necessary to create an index explicitly for primary key columns. WHERE lower (MyColumn) = lower (''); Nov 28, 2019 · postgres=# alter table t2 disable trigger all; ALTER TABLE postgres=# insert into t2 (a,b,c) values (5,5,'ee'); INSERT 0 1 postgres=# alter table t2 enable trigger all; ALTER TABLE postgres=# This will only validate new data but it does not guarantee that all the rows satisfy the constraint: Add primary keys and unique constraints to system catalogs For those system catalogs that have a unique indexes, make a primary key and unique constraint, using ALTER TABLE PRIMARY KEY/UNIQUE USING INDEX. Using SQL Server Management Studio To create a unique constraint. (Edit: this note was removed from the manual with Postgres 9. This Dec 26, 2020 · The name of the tablespace to which the table will be To create a FOREIGN KEY constraint on the "PersonID" column when the "Orders" table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access: ALTER TABLE Orders ADD FOREIGN KEY (PersonID) REFERENCES Persons(PersonID); To allow naming of a FOREIGN KEY constraint, and In PostgreSQL, keys and constraints can be defined on both regular columns and directly on any expression, as long as that expression is immutable CREATE TABLE jsontable (j jsonb NOT NULL) CREATE UNIQUE INDEX j_uuid_idx ON jsontable(((j->>'uuid')::uuid)); ALTER TABLE jsontable ADD CONSTRAINT uuid_must_exist CHECK (j ? 'uuid'); Define PostgreSQL CHECK constraints for existing tables using an ALTER TABLE command In PostgreSQL, we can add the PostgreSQL check constraint for the existing table with the ALTER TABLE command's help. Apply the shared schema strategy in Postgres by using the row-level security policy. Below is parameter description of above syntax: Create: Create table by using unique constraint  The below illustrations of the ALTER TABLE command are used to add a NOT NULL constraint into the existing table: PostgreSQL constraints ensure the accuracy  26 Dec 2020 Third, add a unique constraint to the equipment table using the add, and drop unique constraints in PostgreSQL with syntax and examples. Also, you have to give the constraint a name some_name. Other than that, there is no " MODIFY (like) command" for constraints (referring to MySQL's MODIFY I assume). conname = ccu. 26 Jul 2018 ALTER TABLE customers ADD CONSTRAINT uniquectm_const UNIQUE ( customer_id);. ALTER TABLE table_name ADD CONSTRAINT constraint_name UNIQUE (column1, column2, column_n); To add a (multicolumn) unique constraint to a table: ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode); To add an automatically named primary key constraint to a table, noting that a table can only ever have one primary key: ALTER TABLE distributors ADD PRIMARY KEY (dist_id); PostgreSQL allows you to create a UNIQUE constraint to a group of columns using the following syntax: CREATE TABLE table ( c1 data_type, c2 data_type, c3 data_type, UNIQUE (c2, c3) ); Code language: SQL (Structured Query Language) (sql) The combination of values in column c2 and c3 will be unique across the whole table. We will use the posmulten project to generate the required DDL statements. Oct 08, 2019 · You can’t disable a not null constraint in Postgres, like you can do in Oracle. KEY constraint, CHECK constraint, UNIQUE constraint and the NOT NULL constraint. ALTER TABLE table_name ADD CONSTRAINT [ constraint_name ] UNIQUE(column_list);. The syntax to add constraints to a table column is as follows: . Adding a unique constraint will automatically create a unique B-tree index on the column or column group listed in the constraint 3. In that case, the table is really 'user_1_id` and user_2_id with a unique constraint and a check that user_1_id > user_2_id and let the client figure it out (or worst, case a trigger to swap the values). ALTER TABLE your_table DROP CONSTRAINT constraint_name; Make sure tha the new constraint you wanted to add is unique/ not null ( if its Microsoft Sql, it can contain only one null value) across all data on that table, and then you could re-create it. Column (s) can be added. . oid left join information_schema. FROM MyTable. To add a (multicolumn) unique constraint to a table: ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode); To add an automatically named primary key constraint to a table, noting that a table can only ever have one primary key: ALTER TABLE distributors ADD PRIMARY KEY (dist_id); Sep 27, 2018 · A check constraint is a type of integrity constraint in PostgreSQL which specifies a requirement that must be met by each row in a database table. IV. 4 or later (like you found) can only change the "deferability" of a FK constraints. The idea is to have an index on that column, in a not case sensitive form, i. It can refer to a single column, or multiple columns of the table. ALTER TABLE меняет определение существующей таблицы. However, you can remove the not null constraint from a column and then re-add it to the column. More specifically unique constraints covering all partitions of a partitioned table and INDEX ON child4 (ts); ALTER TABLE child0 ALTER ts SE 21 Sep 2018 I would like to create a table with a table unique constraint on database level. constraint_column_usage ccu on pgc. 2. This can be helpful for GUI tools that look for a primary key, and it might in the future allow declaring foreign keys, for making schema diagrams. ADD SQL Error [23503]: ERROR: insert or update on table " users" violates foreign key constraint "users_ui 2016년 11월 3일 ALTER TABLE editions ADD CONSTRAINT foreign_book FOREIGN KEY ( book_id) REFERENCES books (id); ALTER TABLE editions ADD  5 Feb 2015 Partitioning in PostgreSQL has been an artisanal work for a long time now. Listed below is an example of the SQL generated by the PostgreSQL Alter Table Drop Constraint function: ALTER TABLE sample. PostgreSQL allows you to create a UNIQUE constraint to a group of columns using the following syntax: CREATE TABLE table ( c1 data_type, c2 data_type, c3 data_type, UNIQUE (c2, c3) ); The combination of values in column c2 and c3 will be unique across the whole table. See full list on educba. The following SQL adds a constraint named "PK_Person" that is a PRIMARY KEY constraint on multiple columns (ID and LastName): How to Remove a Not Null Constraint in PostgreSQL. Last modified: February 07, 2021. com Create unique contraint - Using an ALTER TABLE statement. Actually, you should enable / disable the table trigger to achieve this because there are no any direct option for this. table_name, ccu. T The addUniqueConstraint changetype adds a unique constraint to an existing column or ALTER TABLE cat. Sep 11, 2020 · This is the table to which you want to add a unique constraint. Need a good GUI tool for PostgreSQL? Check out  Alter the table to add an unique constraint. Select the name of the tablespace in which the unique constraint will reside from the drop-down listbox in the Tablespace field. ADD CONSTRAINT students_pk PRIMARY KEY (id); When you describe the table with \d tablename command as shown below, there is a constraint added with id as PRIMARY KEY. 6 Aug 2019 There are several constraint put in data when using PostgreSQL. The UNIQUE constraint in PostgreSQL can be applied as a column constraint or a group of column constraint or a table constraint. oid = pgc. The price and discount must be greater than zero and the discount is less than the price. Essa é a tabela de exemplo create table usuario( id serial primary key not null, nome varchar(100), email varchar(100), login varchar(100), senha varchar(100), tipo varchar Creating a Unique constraint using an ALTER TABLE command and adding a unique constraint using a unique index. Column (s) can be dropped. Not null constraints are a great way to add another layer of validation to your data. The constraint creation statements are automatically created by genbki. For set the name that you want to adjust the primary key command for this: # Only adjust this CONSTRAINT unique_identifier PRIMARY KEY (age,zip_code) CREATE TABLE table_name ( column_name UNIQUE ); If you want to add a unique constraint to an existing table, you do it like that: ALTER TABLE table_name ADD CONSTRAINT some_name UNIQUE(column_name); Note that this is different from the ALTER COLUMN syntax for the not-null constraint. person ADD CONSTRAINT const_name UNIQUE   20 Sep 2016 ALTER TABLE users ADD COLUMN foo_factor integer NOT NULL add unique index concurrently, and then add the constraint onto the table:. Constraint (s) can be added. PostgreSQL automatically creates a unique index when a unique constraint : unique => true” should do pretty much the same thing as 19 Feb 2011 Implement ALTER TABLE ADD UNIQUE/PRIMARY KEY USING INDEX. BASIC answers related to “alter constraint postgres” add column in sql; add column sql; add column sql server; add column to table sql; add new column to the table mysql; alter table add multiple columns postgresql; change column type mysql; how to add column to table sql; mysql alter column auto increment; mysql alter table set column unique Add SQL UNIQUE constraint using SQL ALTER TABLE statement You can add a UNIQUE constraint to an existing table using ALTER TABLE statement. 1 An index is added in PostgreSQL, too, when a PRIMARY KEY or a UNIQUE constraint is created, as it is clearly stated in the docs. A PRIMARY KEY constraint automatically has a UNIQUE constraint. ADD CONSTRAINT UNQ_MyTable_MyColumn. table_schema as table_schema, ccu. In the Indexes/Keys dialog box, click Add. 4 docs there was this cautionary note: The preferred way to add a unique constraint to a table is ALTER TABLE ADD CONSTRAINT. pgAdmin - PostgreSQL Tools for Windows, Mac, Linux and the Web. constraint_schema where contype ='c' order by pgc. This is the table that you wish to add a unique constraint to. Assume that we have an existing table in the database, which is named as Amount_list. Here's how to insist that each JSON document is an object: alter table books add constraint books_doc_is_object check  19 Mar 2018 Database constraints are a powerful tool within your Postgres database Usually you would have a unique constraint on your email column. The action to be done by this statement are as follows -. It consists of the field called supplier_id. Select the name of an index from the drop-down listbox in the Index field. This form adds a new PRIMARY KEY or UNIQUE constraint to a table based on an existing unique index. Replace George with  4 Nov 2019 The unique constraints specifically for Oracle/SQL Server is a bit different MySQL and PostgreSQL) alter table user_mapping add constraint  21 Mar 2017 To do that, we add two unique partial indices, one for NOT NULL values and ALTER TABLE unique_nulls_multicolumn ADD CONSTRAINT  Note: If you attempt to add a primary key using ALTER TABLE and any of the A UNIQUE constraint defines a set of columns that uniquely identify rows in a  8 Oct 2019 You can't disable a foreign key constraint in Postgres, like you can do in Oracle. I don ALTER TABLE Employees ADD CONSTRAINT DefaultSalary DEFAULT ((100)) FOR [Salary] This adds a constraint called DefaultSalary which specifies a default of 100 for the Salary column. This feature allows a UNIQUE OR pkey CONSTRAINT TO be created . Add a unique constraint to the cellphones table using the "uni_index" index. Using ALTER in PostgreSQL. hemsire Postgres add unique constraint. You would likewise utilize ALTER TABLE order to add and drop different imperatives on a current table. Both the UNIQUE and PRIMARY KEY constraints provide a guarantee for uniqueness for a column or set of columns. ADD 인덱스를_사용하는_제약조건. ADD CONSTRAINT. In the above syntax, we have used the following  ALTER table table_name add column_name data_type UNIQUE;. The end result should be that only one NULL value is allowed in the nullable_value column. In SQL, tables, databases, schemas, groups, indexes, servers, and more can be modified using the ALTER command. 2019년 7월 31일 테이블명 변경 #### 문법 ``` ALTER TABLE {테이블명} RENAME TO {새 ALTER TABLE editions ADD CONSTRAINT foreign_book FOREIGN KEY CREATE TABLE new_books (id integer UNIQUE, title text NOT NULL,  19 Mar 2019 PostgreSQL is a general purpose and object-relational database management system, the most advanced open source database system  Within the CREATE TABLE command, the syntax for a column constraint follows Note that the UNIQUE constraint allows more than one NULL value to be in a Defines a condition that the value must satisfy for an INSERT or UPDATE . postgres=# ALTER TABLE cellphones ADD CONSTRAINT uni_constraint UNIQUE USING INDEX uni_index; NOTICE: ALTER TABLE / ADD CONSTRAINT USING INDEX will rename index "uni_index" to "uni_constraint" ALTER TABLE postgres=# \d cellphones Table "public. ALTER TABLE I. I figured it out from the PostgreSQL docs, the exact syntax is: ALTER TABLE the_table ADD CONSTRAINT constraint_name UNIQUE  You will learn about PostgreSQL UNIQUE constraint to make sure that values stored ALTER TABLE equipment ADD CONSTRAINT unique_equip_id UNIQUE  ADD table_constraint_using_index. id' )) ) The PostgreSQL ALTER TABLE order is utilized to add, erase or adjust sections in a current table. The ADD CONSTRAINT command is used to create a constraint after a table is already created. lower (MyColumn). Syntax ALTER TABLE table_name ADD CONSTRAINT key_name UNIQUE (column_name); According to psql's inline: \h ALTER TABLE. The tool then generates the appropriate alter table drop constraint SQL command for dropping the constraint from the table. 4 RC2 ~~~~~ template1=# alter table t_a add constraint "a" UNIQUE (email); NOTICE: ALTER TABLE / ADD UNIQUE will create implicit index "a" for table "t_a" ALTER TABLE Apr 13, 2019 · But if you notice we did not provide a name for our primary key, and for this postgres will set a default name following this pattern table-name_pkey. Here’s a quick test case in four steps: Drop a demo table if it exists: Requires ALTER permission on the table. SQL UNIQUE Constraint. Also, it's mentioned in the postgres docs (an excellent resource, plus easy to read, too) like this:. Constraint syntax and example. Primary Key - prevents a duplicate record in the table ADD CONSTRAINT unique_dilek_sikayet_id UNIQUE (id); -- Name: hemsire unique_hemsire_id; Type: CONSTRAINT; Schema: public; Owner: postgres ALTER TABLE ONLY public . When a UNIQUE constraint is adding, an index on a column or Apply the shared schema strategy in Postgres by using the row-level security policy. 5. This requirement now means the table defines a different kind of relationship (no concept of "owner", just "these 2 users are friends"). In fact that's how unique constraints are actually implemented behind the scenes. This section helps you understand altering table columns in Oracle and how you can migrate them to PostgreSQL database. This is done in one atomic statement so that there is no time when there is no constraint on the table. Modify definition of existing table column. However, you can remove the foreign key constraint from a column and then re-add it to the column. Jul 01, 2006 · ALTER TABLE MyTable. This field is optional. This command enables the user to modify a specific aspect of the table, database, group, etc. The syntax for creating a unique constraint. When I first migrated, one problem I had was related to how string columns work. 1; 2. The name will be Use the Fill Factor field to specify a fill factor for the table and index. Add column to table. ERROR: there IS no UNIQUE CONSTRAINT matching given KEYS FOR ALTER TABLE little ADD CONSTRAINT fk_little_1 FOREIGN KEY  The syntax for these various constraints is listed in detail in the section titled Using To implicitly add a unique constraint, a workaround is to create a unique   20 Jul 2018 This creates indexes in PostgreSQL that look like this: execute(""" ALTER TABLE drivers_drivers ADD CONSTRAINT "unique_parent_child"  Check constraints on jsonb columns. ALTER TABLE supplier ADD CONSTRAINT supplier_unique UNIQUE (supplier_id); In this example, we've created a unique constraint on the existing supplier table called supplier_unique. Table contains non-unique values Well the SQL has failed but it was parsed successfully. Spread the word. The use of indexes to enforce unique constraints could be considered an implementation detail that should not be accessed directly.