更新时间:2024-06-29 GMT+08:00
LIMIT
UPDATE LIMIT语法可以用来限制的范围。一个子句是一个行匹配的限制。只要发现满足该子句的行, 语句就会停下来 ,不管它们是否真的发生了变化。
输入示例
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#单独测试 LIMIT 语法点 UPDATE employees SET department_id=department_id+1 LIMIT 3 ; UPDATE employees SET department_id=department_id+1 LIMIT 3 , 10 ; #测试 LIMIT + OFFSET 语法点 UPDATE employees SET department_id=department_id+1 LIMIT 3 OFFSET 2; #测试 LIMIT + ORDER BY 语法点搭配使用 UPDATE employees SET department_id=department_id+1 ORDER BY fname LIMIT 3 ; #测试 LIMIT + WHERE + ORDER BY 语法点搭配使用 UPDATE employees SET department_id=department_id+1 WHERE id<5 ORDER BY fname LIMIT 3 ; #测试 LIMIT + WHERE + ORDER BY + OFFSET 语法点搭配使用 UPDATE employees SET department_id=department_id+1 WHERE id<5 ORDER BY fname LIMIT 3 OFFSET 2 ; |
输出示例
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--单独测试 LIMIT 语法点 UPDATE "public"."employees" SET "department_id" = department_id+1; UPDATE "public"."employees" SET "department_id" = department_id+1; --测试 LIMIT + OFFSET 语法点 UPDATE "public"."employees" SET "department_id" = department_id+1; --测试 LIMIT + ORDER BY 语法点搭配使用 UPDATE "public"."employees" SET "department_id" = department_id+1; --测试 LIMIT + WHERE + ORDER BY 语法点搭配使用 UPDATE "public"."employees" SET "department_id" = department_id+1 WHERE id<5; --测试 LIMIT + WHERE + ORDER BY + OFFSET 语法点搭配使用 UPDATE "public"."employees" SET "department_id" = department_id+1 WHERE id<5; |
父主题: UPDATE