golang查询数据库没有数据时返回值问题

最新推荐文章于 2024-01-31 17:52:21 发布

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#golang #mysql #query #nil

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在使用Golang的database/sql包操作MySQL数据库时，如果查询无结果，会返回err为nil，表示没有错误。rows变量并不会返回nil，而是一个结构体的内存地址，表明查询操作已完成但未找到记录。

使用golang的datadase/sql包进行mysql数据库查询，没有查询到结果时，返回值是多少

sqlStr := "select distinct domain from securitymanager.domainthreat where ip =?"
	rows, err := db.Query(sqlStr, "222.73.219.63")

没有查询到数据时返回值：

返回的err为nil，没有查询到数据是正常的情况，不会报错
rows不是nil！而是一个结构体的内存地址，比如&{0xc042096080 0x4c89e0 0xc042078140 0x4ba8d0 0xc04203a1c0 {{0 0} 0 0 0 0} false <nil> []}
rows结构体格式

type Rows struct {
	dc          *driverConn // owned; must call releaseConn when closed to release
	releaseConn func(error)
	rowsi       driver.Rows
	cancel      func()      // called when Rows is closed, may be nil.
	closeStmt   *driverStmt // if non-nil, statement to Close on close

	// closemu prevents Rows from closing while there
	// is an active streaming result. It is held for read during non-close operations
	// and exclusively during close.
	//
	// closemu guards lasterr and closed.
	closemu sync.RWMutex
	closed  bool
	lasterr error // non-nil only if closed is true

	// lastcols is only used in Scan, Next, and NextResultSet which are expected
	// not to be called concurrently.
	lastcols []driver.Value
}