SQL Server/T-SQL/Constraints/Constraints Basics

Enable a column to optionally not require a value by designating it as a nullable column

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1> -- Nullability 2> 3> -- Enable a column to optionally not require a value by designating it as a 4> -- nullable column. 5> 6> CREATE TABLE MyTable 7> ( Category nVarChar(50) NOT NULL 8> , MyDescription nVarChar(50) 9> ) 10> INSERT MyTable (Category) VALUES ("Category1") 11> 12> SELECT * FROM MyTable 13> GO (1 rows affected) Category MyDescription

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Category1 NULL (1 rows affected) 1> 2> drop table MyTable 3> GO 1>

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NOT NULL column and NULL column

   <source lang="sql">

1> CREATE TABLE MyTable 2> ( Category nVarChar(50) NOT NULL 3> , MyDescription nVarChar(50) NULL 4> ) 5> 6> 7> INSERT MyTable (Category) VALUES ("Category1") 8> 9> SELECT * FROM MyTable 10> GO (1 rows affected) Category MyDescription

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Category1 NULL (1 rows affected) 1> 2> drop table MyTable 3> GO 1>

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