Sql update if primary key exists
Names, descriptions, etc, exist once, in one row. Keys exist wherever they have been migrated. And if the "key" is a RID, then the RID too, exists wherever it has been migrated. Don't update the PK! is the second-most hilarious thing I have read in a while. Add a new column is the most.Nov 08, 2017 · DECLARE @IsPrimary INT SELECT @IsPrimary=COUNT(1) FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE OBJECTPROPERTY(OBJECT_ID(CONSTRAINT_SCHEMA + '.' + QUOTENAME(CONSTRAINT_NAME)), 'IsPrimaryKey') = 1 AND TABLE_NAME = 'PromotionBenefit' IF @IsPrimary>0 BEGIN SELECT 'Table already have Primary Key' END ELSE BEGIN ALTER TABLE PromotionBenefit ADD CONSTRAINT PK_PromotionBenefit2 PRIMARY KEY CLUSTERED (PromotionBenefitCode); GO END
Aug 06, 2013 · Primary Key Such type of candidate key which is chosen as a primary key for table is known as primary key. Primary keys are used to identify tables. There is only one primary key per table. In SQL Server when we create primary key to any table then a clustered index is automatically created to that column. Foreign Key Jul 18, 2017 · The primary key enforces the entity integrity of the table. All columns defined must be defined as NOT NULL. The primary key uniquely identifies a row. Primary keys result in CLUSTERED unique indexes by default. As you can see, the primary key is the main key of the table. Its main purpose is to identify each row. Description. dblink_build_sql_update can be useful in doing selective replication of a local table to a remote database. It selects a row from the local table based on primary key, and then builds a SQL UPDATE command that will duplicate that row, but with the primary key values replaced by the values in the last argument.
Aug 29, 2016 · This is particularly important in case you need to update or delete a specific row. Relationships. The primary key is frequently used in related tables to tie the two tables together. Typically this is a Foreign Key relationship. The smaller the key the less space taken up in the other tables. The smaller the key the smaller the related index.