if-else, case, etc. TheCASEstatement is one of the conditional expressions that is used to create conditional queries. PostgreSQL allows us to use the WHEN-THEN case, if-else statements, etc. with the CASE statement to create or formulate a query/expression. ...
cur cursor for select * from t10 order by f1; step1 语法树 代码语言:javascript 代码运行次数:0 运行 AI代码解释 decl_statement : decl_varname decl_const decl_datatype decl_collate decl_notnull decl_defval { ... } /* 【第一步】 */ /* 执行到这里的时候decl_varname、opt_scrollable都解...
行操作, (如果SQL语句涉及多行, 则跳到下一行的第一个before for each row触发器; 如果SQL不涉及多行或者已经到达最后行, 则直接跳到语句结束或after for each statement的操作;) 3. before for each row(可选) 4. 检查约束, 插入行的操作 5. 以下触发器或returning语句的NEW值取自HeapTuple, 表示物理的...
Keep in mind that, the column must be present in the SELECT statement of your query, on which you are specifying the boolean expressions (in CASE). But when you are using CASE in pair with a where clause, you need not to follow this (more on this later). The data-type of the ...
MyTest=# SELECT set_config('log_statement_stats','off', false); set_config --- off (1 row) 2. 数据库对象尺寸函数: 名字 返回类型 描述 pg_tablespace_size(oid) bigint 指定OID代表的表空间使用的磁盘空间 pg_tablespace_size(name) bigint 指定名字的表空间使用的磁盘空间 pg_database_size(oid...
搜索CASE 表达式可以构造任意复杂的判断逻辑,实现 IF 语句的各种功能。 循环语句 PostgreSQL 提供了 4 种循环执行命令的语句:LOOP、WHILE、FOR 和 FOREACH 循环,以及循环控制的 EXIT 和 CONTINUE 语句。 首先,LOOP 用于定义一个无限循环语句: [<>]LOOPstatementsENDLOOP[label]; 一般需要...
end case; --CASE表达式 --变量 :=case ...(上述两种方式,但statement为对于类型的value) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 循坏语句 AI检测代码解析 --1、LOOP循环 LOOP STATEMENT1;... EXIT WHEN CONDITION1;--或使用IF C1 THEN EXIT END IF;语句 END...
CASE statements The CASE statement uses IF-THEN-ELSE logic within a single statement. It facilitates conditional inquiries by doing the work of an IF-THEN-ELSE statement and applying it to many possible conditions. Syntax CASE condition WHEN condition value THEN statement ELS...
case 'E': /* error return */ case 'Z': /* backend is ready for new query */ case 'I': /* empty query */ case '1': /* Parse Complete */ case '2': /* Bind Complete */ case '3': /* Close Complete */ case 'S': /* parameter status */ ...
SELECT'GRANT USAGE ON SCHEMA '||schemaname||' TO readonly_user;'as"GrantStatement"FROM(SELECTDISTINCT(table_schema)ASschemanameFROMinformation_schema.tablesWHEREtable_schemaNOTIN('pg_catalog','information_schema')ORDERBYtable_schema ) t;