我有一个有效的解决方案: FOR target IN query LOOP statements END LOOP; 但我想做这样的事情: FOR target IN (IF condition_1 THEN query_1 ELSE query_2 END IF) LOOP statements END LOOP; 但是我不能去上班。我也尝试过这个版本,但它也不起作用: FOR target IN (CASE WHEN condition_1 THEN query...
3. IF-THEN-ELSIF 有时有两个以上的选择。IF-T-ELSIF提供了一种方便的检查几种替代方案的方法。对IF条件进行连续测试直到找到第一个IF条件为止。然后执行关联的语句,之后控制在结束if之后传递给下一个语句。(任何后续的if条件未被测试)如果没有IF条件是真的,则执行另一个块(如果有的话)。 IF boolean-expressi...
CREATE OR REPLACE FUNCTION execute_sql_conditionally(condition boolean) RETURNS void AS $$ BEGIN IF condition THEN EXECUTE 'SELECT * FROM table1'; ELSE EXECUTE 'SELECT * FROM table2'; END IF; END; $$ LANGUAGE plpgsql; 在上述示例中,函数execute_sql_conditionally接受一个布尔类型的参数c...
For inline conditional logic in SQL queries. Using IF in PL/pgSQL The IF statement in PL/pgSQL allows developers to execute conditional operations within a procedural block. Syntax: DO $$ BEGIN IF condition THEN -- Statements to execute if condition is true ELSIF other_condition THEN -- Sta...
[ WITH [ RECURSIVE ] with_query [, ...] ] SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] [ * | expression [ [ AS ] output_name ] [, ...] ] [ FROM from_item [, ...] ] [ WHERE condition ] [ GROUP BY grouping_element [, ...] ] ...
定义一个游标。DECLARE name [ BINARY ] [ INSENSITIVE ] [ [ NO ] SCROLL ] CURSOR [ { WITH | WITHOUT } HOLD ] FOR query [ FOR { READ ONLY | UPDATE [ OF column [, ...] ] } ]DELETE删除一个表中的行。DELETE FROM [ ONLY ] table [ WHERE condition ]...
IF...THEN...ENDIF;IF...THEN...ELSE...ENDIF;IF...THEN... ELSIF ...THEN...ELSE...ENDIF; 以及两种形式的CASE: CASE...WHEN...THEN...ELSE...ENDCASE;CASEWHEN...THEN...ELSE...ENDCASE; 2|11.1 IF条件语句 语法结构: IFsearch_conditionTHENstatement_listENDIF;---IFsearch_conditionTHENst...
If [condition] then statement1 ELSE statement2 END IF; 1. 2. 3. 4. 5. 循环结构 DECLARE v_count binary_integer := 1 /* LOOP循环 */ BEGIN LOOP insert into tmp_table(num_col) value (v_count); v_count := v_count + 1; EXIT WHEN v_count > 50; END LOOP; END; /* FOR循环 ...
IF 语句可以基于条件选择性执行操作, PL/pgSQL 提供了三种形式的 IF 语句。 IF ... THEN ... END IF IF ... THEN ... ELSE ... END IF IF ... THEN ... ELSIF ... THEN ... ELSE ... END IF 首先,最简单的 IF 语句如下: IF boolean-expression THEN statements END IF; 如果表达式 bool...
if (conditionA == true) { await pool.query(query1) } if (conditionB == true) { await pool.query(query2) } 运行它们会导致一个错误:SyntaxError: await is only valid in async function,原点位于await pool.query(query1)。 删除await会导致无法解析的承诺错误。