CONSTRAINT名字 (可选)指定约束的名称。 该名称在架构中必须唯一。 如果未提供任何名称,Azure Databricks 会生成一个。 PRIMARY KEY ( key_column [ TIMESERIES ] [, ...] ) [ constraint_option [...] ] 适用于:仅 Unity Catalog 向关系添加主键约束。 关系最多可以有
We can also add theUNIQUEconstraint to an existing column using theALTER TABLEcommand. For example, For a Single Column -- add unique constraint to an existing columnALTERTABLECollegesADDUNIQUE(college_id); Here, the SQL command adds theUNIQUEconstraint to thecolleges_idcolumn in the existingColl...
CHECK constraint is used to limit the range of the values, that can be entered for a column. Let's say, we have an integer AGE column, in a table. The AGE in general cannot be less than ZERO and at the same time cannot be greater than 150. But, since AGE is an integer column ...
Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Specifies the properties of a PRIMARY KEY, FOREIGN KEY, UNIQUE, or CHECK constraint that is part of a new column definition added to a table by using ALTER TABLE. Note For Microsoft Fabric, visit ALTER TABLE column_...
] type_name REBUILD [ [ NONCLUSTERED ] WITH ( BUCKET_COUNT = bucket_count ) ] } | ADD { <column_definition> | <computed_column_definition> | | | <column_index> } [ ,...n ] | DROP [ { CONSTRAINT [ IF EXISTS ] { constraint_name } [ ,...n ] | INDEX [ IF EXISTS ] ...
ADD COLUMN DROP COLUMN SET TBLPROPERTIES UNSET TBLPROPERTIES 修改PREDICTIVE OPTIMIZATION 如果您使用 Unity Catalog,您必須擁有MANAGE許可權或擁有下列所有權: SET OWNER TO 執行所有其他作業需要具有資料表的所有權。 重新命名 COLUMN ADD CONSTRAINT 將檢查約束、資訊性外鍵約束或資訊性主鍵約束新增至資料表。
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); ...
ALTER TABLE fails and an error is returned. When a new PRIMARY KEY or UNIQUE constraint is added to an existing column, the data in the column or columns must be unique. If duplicate values are found, ALTER TABLE fails. TheWITH NOCHECKoption has no effect when PRIMARY KEY or UNIQUE cons...
Add a LONG, LOB, or object type column or change the datatype of an external table column to any of these datatypes. Add a constraint to an external table. Modify the storage parameters of an external table. Specify LOGGING or NOLOGGING. Specify MOVE Note: If you alter a table...
ADD column_name tada_type NOT NULL CONSTRAINT constraint_name DEFAULT default_value; If you set the new column nullable, that column value for all existing rows will be NULL instead of the default value. In that case, you can addWITH VALUESto the statement: ...