CHECK Constraint in Existing Table We can add theCHECKconstraint to an existing table by using theALTER TABLEclause. For example, let's add theCHECKconstraint to theamountcolumn of an existingOrderstable. -- add CHECK constraint without nameALTERTABLEOrdersADDCHECK(amount >0); Here's how we c...
Once defined, the database will only insert a new row or update an existing row if the new value satisfies the CHECK constraint. The CHECK constraint is used to ensure data quality. For example, in the following CREATE TABLE statement, ...
可以使用 SQL Server Management Studio 或 Transact-SQL 在表中创建检查约束,以指定 SQL Server 的一个或多个列中可接受的数据值。 要详细了解如何添加列约束,请参阅 ALTER TABLE column_constraint。 有关详细信息,请参阅 Unique 约束和 check 约束。 备注 若要查询现有的检查约束,请使用 sys.check_constraints...
If you define aCHECKconstraint on a table it can limit the values in certain columns based on values in other columns in the row. SQL CHECK on CREATE TABLE The following SQL creates aCHECKconstraint on the "Age" column when the "Persons" table is created. TheCHECKconstraint ensures that ...
Check constraint is used to validate values entered into a column. CHECK constraints enforce domain integrity by limiting the values that are accepted by a column. They are similar to FOREIGN KEY constraints in that they control the values that are place
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例如,我想添加一个检查约束ADD CONSTRAINTcheck_colourCHECK(color IN ('black','white', 'green')) 我可以在命令行中执行此操作,但是在MysqlWorkbench中找不到添加检查约束的选项。我只能找到触发器,但不能找到check约束。 浏览10提问于2015-07-20得票数4 ...
Azure SQL 受控執行個體 檢查目前資料庫中之指定資料表的指定條件約束或所有條件約束的完整性。 Transact-SQL 語法慣例 語法 syntaxsql DBCCCHECKCONSTRAINTS[ (table_name|table_id|constraint_name|constraint_id) ] [WITH[ {ALL_CONSTRAINTS|ALL_ERRORMSGS} ] [ , ] [NO_INFOMSGS] ]...
SQL Server Azure SQL 数据库 Azure SQL 托管实例 检查当前数据库中指定表上的指定约束或所有约束的完整性。 Transact-SQL 语法约定 语法 syntaxsql DBCCCHECKCONSTRAINTS[ (table_name|table_id|constraint_name|constraint_id) ] [WITH[ {ALL_CONSTRAINTS|ALL_ERRORMSGS} ] [ , ] [NO_INFOMSGS] ] ...
Example Let's look at an example of how to use the ALTER TABLE statement to create a check constraint in SQL Server. For example: ALTER TABLE employees ADD CONSTRAINT check_last_name CHECK (last_name IN ('Smith', 'Anderson', 'Jones')); In this example, we've created a check constrai...