在PostgreSQL中,ON DELETE RESTRICT是一种外键约束选项,用于控制当被引用表中的数据行被删除时,引用表中的数据行如何响应。下面是关于ON DELETE RESTRICT的详细解释和示例: 解释什么是"ON DELETE RESTRICT": ON DELETE RESTRICT是一种外键约束,它规定如果尝试删除被引用表中的数据行,而这些数据行在引用表中被其他数...
# RESTRICT 和 NO ACTION 具有相同的语义,两者本质不同在于 NO ACTION 允许关联检查推迟到事务的最后,而 RESTRICT 则会马上报错。 # SET NULL 主表在 on delete/update 时,设置从表外键为 NULL。 # SET DEFAULT 主表在 on delete/update 时,设置从表外键为 DEFAULT(默认值)。 CREATE TABLE products ( produ...
An ODATA filter query to restrict the entries returned (e.g. stringColumn eq 'string' OR numberColumn lt 123). Order By $orderby string An ODATA orderBy query for specifying the order of entries. Top Count $top integer Total number of entries to retrieve (default = all). Skip Co...
We want to add a column named color to our cars table.When adding columns we must also specify the data type of the column. Our color column will be a string, and we specify string types with the VARCHAR keyword. we also want to restrict the number of characters to 255:Example Add a...
MINUTETOSECOND 布尔类型 枚举类型 声明 CREATETYPE moodASENUM ('sad','ok','happy'); 使用 CREATETYPE moodASENUM ('sad','ok','happy'); CREATETABLEperson ( name text, current_mood mood ); INSERTINTOpersonVALUES('Moe','happy'); SELECT*FROMpersonWHEREcurrent_mood='happy'; ...
array_to_string(c.conkey, ' ') AS constraint_key, CASE confupdtype WHEN 'a' THEN 'NO ACTION' WHEN 'r' THEN 'RESTRICT' WHEN 'c' THEN 'CASCADE' WHEN 'n' THEN 'SET NULL' WHEN 'd' THEN 'SET DEFAULT' END AS on_update, CASE confdeltype WHEN 'a' THEN 'NO ACTION...
RESTRICT:It will not allow you to delete the view if any dependent object exists. The following command will remove the view called ‘postgresql_view’: DROP VIEW 'postgresql_view'; Conclusion We hope you have understood the concept of PostgreSQL views. And also learned about how to create, ...
This is because SELinux might restrict the users to log in to the PostgreSQL. Just enter the following command to get rid of this error. setsebool -P httpd_can_network_connect_db 1 Now, you’ll be able to log in to the Dashboard without any problems. This is how my phpPgAdmin dash...
How to Drop the Table in PostgreSQL? Below we will learn about the drop table: Syntax: DROP TABLE [IF EXISTS] table_name [CASCADE | RESTRICT]; In order to delete the table from the database, you need to define the name of the table after the DROP TABLE keyword. ...
SQL> startup mount exclusive restrict; Finally, drop the database with the following command: SQL> drop database; To check the installed version of Oracle, run the command below: SQL> SELECT * FROM V$VERSION; To view the database name, run the following command: ...