其中,table_name是要修改的表名,column_name是要修改的列名,new_default_value是要修改的新默认值。 ALTER COLUMN语句的应用场景包括但不限于以下情况: 当需要修改表的列的数据类型时,可以使用ALTER COLUMN语句进行修改。 当需要修改表的列的约束条件时,可以使用ALTER COLUMN语句进行添加或删除非空约束。 当需要修改...
ALTER [ COLUMN ] column TYPE type [ USING expression ] ALTER [ COLUMN ] column SET DEFAULT expression ALTER [ COLUMN ] column DROP DEFAULT ALTER [ COLUMN ] column { SET | DROP } NOT NULL ALTER [ COLUMN ] column SET STATISTICS integer ALTER [ COLUMN ] column SET STORAGE { PLAIN | EXT...
ALTERTABLEemployeesALTERCOLUMNhire_dateDROPDEFAULT; 4.3 修改列的约束 要更改列的约束(如NOT NULL),可以使用以下语法: ALTERTABLEtable_nameALTERCOLUMNcolumn_nameSETNOTNULL;ALTERTABLEtable_nameALTERCOLUMNcolumn_nameDROPNOTNULL; 示例: 将email列设置为NOT NULL: ALTERTABLEemployeesALTERCOLUMNemailSETNOTNULL; 将em...
5、更改列的名字ALTERTABLEtable_nameRENAMEcolumn_name to new_column_name; 6、字段的notnull设置ALTERTABLEtable_nameALTERcolumn_name{SET|DROP}NOTNULL; 7、给列加入defaultALTERTABLEtable_nameALTERcolumn_nameSETDEFAULTexpression;
ALTER COLUMN emp_id SET NOT NULL; The above command will add a “NOT NULL” constraint in the “emp_id” column: Let’s verify the table’s alteration using the following command: \d emp_data; The “NOT NULL” constraint has been added to the emp_id column. ...
ALTER TABLE distributors ALTER COLUMN street SET NOT NULL; ###To remove a not-null constraint from a column: ALTER TABLE distributors ALTER COLUMN street DROP NOT NULL; ###To add a check constraint to a table and all its children:
您需要在创建表之前 *SET ROLE*，以便角色成为表的所有者。只有表的所有者才能ALTER表。
7 Add a new column to a view in SQL 0 How to I create column in view 4 Add a new column to a Postgres materialized view 0 PostgreSQL: How to modify values in view 1 Add column to View without using ALTER TABLE Hot Network Questions In this position, why is the move 12....
开发者ID:akema-fr,项目名称:fluentmigrator,代码行数:12,代码来源:PostgresGenerator.cs 示例3: GetAlterColumnExpression ▲点赞 3▼ publicstaticAlterColumnExpressionGetAlterColumnExpression(){varexpression =newAlterColumnExpression(); expression.TableName = TestTableName1; ...
I'm running Postgres 13.3. The use case is creating a history table such that I can insert the transition table of statement-level trigger into the history table. I can't do a blind insert from a select because the transition table rows include the generated column. postgresql alter-table ...