Sql Query To Find Unique Constraints On A Table

September 22, 2021

Query below lists all table and view constraints - primary keys unique key constraints and indexes foreign keys and check and default constraints. The constraint information is in sysconstraints system object.

Sql Server Create Unique Constraint On Table Column On Existing Table Sql Authority With Pinal Dave

The query is as follows.

Sql query to find unique constraints on a table. It returns a boolean value indicating the presenceabsence of duplicate tuples. DROP a UNIQUE Constraint. Query for checking constraints on this table.

ALTER TABLE CUSTOMERS DROP INDEX myUniqueConstraint. Mysql create table UniqueConstraint - - Id int - FirstName varchar30 - LastName varchar30 - constraint uniqueFirstNameAndLastName UNIQUEFirstNameLastName -. Or if we can get create table statement for that table not from sql server.

Select schema_nametschema_id tname as table_view case when ttype U then Table when ttype V then View end as object_type case when ctype PK then Primary key when ctype UQ then Unique constraint when itype 1 then Unique clustered index when itype 2 then Unique index end as constraint_type cname as constraint_name. The query is as. Easiest way to check for the existence of a constraint and then do something such as drop it if it exists is to use the OBJECT_ID function.

Sql query to find unique constraints on a table. If you are using MySQL then you can use the following syntax. SQL query to find unique column values from table.

SELECT FROM INFORMATION_SCHEMA. Example of UNIQUE Constraint. WHERE TABLE_NAME Employee AND TABLE_SCHEMA STTest.

Select from INFORMATION_SCHEMATABLE_CONSTRAINTS where CONSTRAINT_TYPEUNIQUE and table_namedb_my_table. Unique constraint in SQL is used to check whether the sub query has duplicate tuples in its result. MySQL SQL Server Oracle MS Access.

SELECT CONSTRAINT_NAME SEARCH_CONDITION AS CONSTRAINT_TYPE FROM USER_CONSTRAINTS WHERE TABLE_NAMESDF. Here we have a simple CREATE query to create a table which will have a column s_id with unique values. A T-SQL find constraints on table is shown below.

Lets say we already have a table ConstraintDemo. Pin On Apexsql Blog. Query below lists all table and view constraints primary keys unique key constraints and indexes foreign keys and check and default constraints.

You can even filter data by specific constraint type schema name table name etc. Adding unique key constraint to multiple columns. Unique construct returns true only if the sub query has no duplicate tuples else it return false.

Mysql select COLUMN_NAME CONSTRAINT_NAME REFERENCED_COLUMN_NAME REFERENCED_TABLE_NAME from information_schemaKEY_COLUMN_USAGE where TABLE_NAME ConstraintDemo. If a UNIQUE constraint is added to a column that has duplicated values the Database Engine returns an error and does not add the constraint. ALTER TABLE CUSTOMERS ADD CONSTRAINT myUniqueConstraint UNIQUEAGE SALARY.

Adding unique key constraint to a column. ALTER TABLE ADD UNIQUE. To find any unique constraint on a table.

Unique construct returns true only if the sub query has no duplicate tuples else it return false. Query to find unique constraints on a table in oracle SQL CREATE TABLE DEPT_MASTER dept_nr NUMBER UNIQUE dept_name varchar2100 NOT NULL dept_status NUMBER10 NOT NULL created_at date. When a UNIQUE constraint is added to an existing column or columns in the table by default the Database Engine examines the existing data in the columns to make sure all values are unique.

The above query will find all UNIQUE key constraints. Select from INFORMATION_SCHEMAKEY_COLUMN_USAGE where CONSTRAINT_NAMEcons_name and. SQL UNIQUE Constraint on ALTER TABLE To create a UNIQUE constraint on the ID column when the table is already created use the following SQL.

ALTER TABLE ADD CONSTRAINT UNIQUE. SQL select CONSTRAINT_NAMEINDEX_NAMECONSTRAINT_TYPE from user_constraints where. Tablename DROP CONSTRAINT CK_ConstraintName.

We have a table in which we want to know whether any of the columns has unique constraint defined. ALTER TABLE CUSTOMERS DROP CONSTRAINT myUniqueConstraint. Query OK 0 rows affected 074 sec Implement the above syntax to display the name of the constraint which is a unique constraint from a MySQL table.

And TCCONSTRAINT_TYPE PRIMARY KEY. SQL query to find unique values of column department from Geeks table. Limits whole table data.

CK_ConstraintName C IS NOT NULL ALTER TABLE dbo. We take a sample table named Geeks and return unique column values by applying various SQL queries on it. --Lets insert a row into the table.

Query select table_view object_type constraint_type constraint_name details from select schema_nametschema_id tname as table_view case when ttype U then Table when ttype V then View end as object_type. The above query will declare that the s_id field of Student table will only have unique values and wont take NULL value. ALTER TABLE demo ADD UNIQUE PHONE.

Following query will result the correct answer. To display all constraints on a table implement the above syntax. To find the primary key replace the last line with.

However it will not find PRIMARY KEY constraints or UNIQUE indexes that were created outside a UNIQUE key constraint. List all the constraint in a table Employee under Schema STTest. To drop a UNIQUE constraint use the following SQL query.

CREATE TABLE Student s_id int NOT NULL name varchar 60 age int NOT NULL UNIQUE. The sysconstraintsconstid is the object_id of the constraints object in sysobjects table and sysconstraintsid is the object_id of the table that the constraints belong too. To find unique column list with all column.

Difference Between Unique Indexes And Unique Constraints In Sql Server