golang - mysql一次插入多个数据？

Question

我知道一次插入多个数据的效率更高:

INSERT INTO test(n1, n2, n3) 
VALUES(v1, v2, v3),(v4, v5, v6),(v7, v8, v9);

如何在golang中做到这一点？

data := []map[string]string{
   {"v1":"1", "v2":"1", "v3":"1"},
   {"v1":"2", "v2":"2", "v3":"2"},
   {"v1":"3", "v2":"3", "v3":"3"},
}
//I do not want to do it
for _, v := range data {
    sqlStr := "INSERT INTO test(n1, n2, n3) VALUES(?, ?, ?)"
    stmt, _ := db.Prepare(sqlStr)
    res, _ := stmt.Exec(v["v1"], v["v2"], v["v3"])
}

使用字符串拼接,但它并不好.db.Prepare更安全吧？

sqlStr := "INSERT INTO test(n1, n2, n3) VALUES"
for k, v := range data {
    if k == 0 {
        sqlStr += fmt.Sprintf("(%v, %v, %v)", v["v1"], v["v2"], v["v3"])
    } else {
        sqlStr += fmt.Sprintf(",(%v, %v, %v)", v["v1"], v["v2"], v["v3"])
    } 
}
res, _ := db.Exec(sqlStr)

我需要一个功能更安全,更有效的插入多个数据.

Answer 1

为什么不是这样的？(写这里没有测试,所以可能有语法错误):

sqlStr := "INSERT INTO test(n1, n2, n3) VALUES "
vals := []interface{}{}

for _, row := range data {
    sqlStr += "(?, ?, ?),"
    vals = append(vals, row["v1"], row["v2"], row["v3"])
}
//trim the last ,
sqlStr = sqlStr[0:len(sqlStr)-2]
//prepare the statement
stmt, _ := db.Prepare(sqlStr)

//format all vals at once
res, _ := stmt.Exec(vals...)

Answer 2

对于 Postgres lib pq 支持批量插入：https : //godoc.org/github.com/lib/pq#hdr-Bulk_imports

但是同样可以通过下面的代码实现，但真正有用的是当人们尝试执行批量条件更新（相应地更改查询）时。

要为 Postgres 执行类似的批量插入，您可以使用以下函数。

// ReplaceSQL replaces the instance occurrence of any string pattern with an increasing $n based sequence
func ReplaceSQL(old, searchPattern string) string {
   tmpCount := strings.Count(old, searchPattern)
   for m := 1; m <= tmpCount; m++ {
      old = strings.Replace(old, searchPattern, "$"+strconv.Itoa(m), 1)
   }
   return old
}

所以上面的样本变成

sqlStr := "INSERT INTO test(n1, n2, n3) VALUES "
vals := []interface{}{}

for _, row := range data {
   sqlStr += "(?, ?, ?),"
   vals = append(vals, row["v1"], row["v2"], row["v3"])
}

//trim the last ,
sqlStr = strings.TrimSuffix(sqlStr, ",")

//Replacing ? with $n for postgres
sqlStr = ReplaceSQL(sqlStr, "?")

//prepare the statement
stmt, _ := db.Prepare(sqlStr)

//format all vals at once
res, _ := stmt.Exec(vals...)