使用用户定义的变量指定列别名 [英] Specifying column alias with user-defined variable
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问题描述
我想使用用户定义的变量重命名查询的列.
I want to rename the columns of a query by using user-defined variables.
例如:
select id as @rt from table_name
推荐答案
这是不可能的.您必须动态创建 sql 字符串.
This is not possible. You would have to create the sql string dynamically.
C#:
string columnName = "xy";
string sql = "SELECT id AS " + columnName + " FROM table_name";
VB:
Dim columnName As String = "xy"
Dim sql As String = "SELECT id AS " & columnName & " FROM table_name"
您也可以在 MySql 的存储过程中执行此操作.有关预处理语句的 SQL 语法一个>
You can also do that in a stored procedure with MySql. See MySql documentation for SQL Syntax for Prepared Statements
它看起来像这样(未经测试):
It would look something like this (not tested):
CREATE PROCEDURE myProc (columnName VARCHAR(30))
BEGIN
SET @sql = CONCAT("SELECT id AS ", columnName, " FROM table_name");
PREPARE s1 FROM @sql;
EXECUTE s1;
DEALLOCATE PREPARE s1;
END$$
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