sql server 奇葩問題

SELECT DISTINCT
	a.*
FROM
	employeeInfo a
LEFT JOIN (
	SELECT
		b.buiness
	FROM
		quaData b,
		qualificationsInfo c
	WHERE
		b.qualificationsInfoId = c.qualificationsInfoId
	AND c.qfType = 1
	AND c.state = 1
	AND b.state = 1
) dd ON a.employeeInfoId = dd.buiness

SELECT
	a.*
FROM
	employeeInfo a
LEFT JOIN (
	SELECT
		b.buiness
	FROM
		quaData b,
		qualificationsInfo c
	WHERE
		b.qualificationsInfoId = c.qualificationsInfoId
	AND c.qfType = 1
	AND c.state = 1
	AND b.state = 1
) dd ON CONVERT (
	VARCHAR (100),
	a.employeeInfoId
) = dd.buiness

其中quaData中的buiness字段是varchar類型的，存的值是英文和數字。

第一段代碼去掉distinct就不行了，會報錯：[Err] 22018 - [SQL Server]在將 varchar 值 'e10c9cb3d30b4b4cb1721561a31db513' 轉換成數據類型 int 時失敗。

不用distinc卻確實t會有重複的結果