MYSQL SELECT 语句中是否可以包含取决于用户选择的条件?为了清楚起见进行了编辑。 这样做的东西:
IF user *does A* SELECT * FROM myTable
IF user *does B* SELECT colB, colC, colD FROM myTable
ELSE SELECT * FROM myTable WHERE ID < 5
原始帖子引用了专有前端,但我只是想看看是否有单独 MYSQL 查询的解决方案。
我有一个 MYSQL 查询,它根据列值的下拉选择返回表的过滤视图。如果下拉列表不与列中的值匹配或者用户选择“显示全部”,我想包含一个“返回表格的全部”选项。像这样的:
有没有办法像这样使用 ELSE:
SELECT colA FROM mytable
WHERE *userChoice* = colA
ELSE SELECT * FROM myTable
或者,我认为可以用 case 语句来完成,但我无法弄清楚语法:
CASE
WHEN userPick = colA THEN SELECT colA FROM myTable
WHEN userPick = colB THEN SELECT colB FROM myTable
WHEN userPick = selectAll THEN SELECT * FROM myTable
ELSE SELECT * FROM myTable
END
我想在查询中添加一个子句,如果用户不
CREATE DEFINER=`root`@`localhost` PROCEDURE `test`(input VARCHAR(15))
BEGIN
SET @input = input;
if @input="asc" then
SET @sort = " order by ActivityLogKey asc";
elseif @input = "desc" then
SET @sort = " order by ActivityLogKey desc";
else
SET @sort ="";
end if;
SET @query = CONCAT('select * from activitylog ',@sort,' limit 0, 5');
PREPARE stmt FROM @query;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END