Question

我正在尝试从表B的结果集中插入表A：

INSERT INTO A (x, y, created_at) 
(SELECT x, "something", a_timestamp 
FROM B WHERE c IS NULL AND a_timestamp > NOW())

问题是，对于某些情况

(SELECT x, "something", a_timestamp 
FROM B WHERE c IS NULL AND a_timestamp > NOW())

不返回任何记录（可以），但是其他INSERT失败。

如何从这种情况中掩饰自己？

谢谢！

Answer 1

我无法重现错误：

mysql> DROP TABLE IF EXISTS `tbl_test`;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> CREATE TABLE IF NOT EXISTS `tbl_test` (
    ->   `id` TINYINT
    -> );
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO `tbl_test`
    -> SELECT 1
    -> FROM DUAL
    -> WHERE 0 = 0;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> SELECT `id` FROM `tbl_test`;
+------+
| id   |
+------+
|    1 |
+------+
1 row in set (0.00 sec)

mysql> INSERT INTO `tbl_test`
    -> SELECT 1
    -> FROM DUAL
    -> WHERE 0 = 1;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> SELECT `id` FROM `tbl_test`;
+------+
| id   |
+------+
|    1 |
+------+
1 row in set (0.00 sec)

<强>更新

mysql> DROP TABLE IF EXISTS `tbl_test`;
Query OK, 0 rows affected (0.00 sec)

mysql> CREATE TABLE IF NOT EXISTS `tbl_test` (
    ->   `id` TINYINT
    -> );
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO `tbl_test`
    ->   (`id`)
    -> VALUES
    ->   (101);
Query OK, 1 row affected (0.00 sec)

mysql> SELECT `id`
    -> FROM `tbl_test`;
+------+
| id   |
+------+
|  101 |
+------+
1 row in set (0.00 sec)

mysql> INSERT INTO `tbl_test`
    -> SELECT `id` + 1
    -> FROM `tbl_test`
    -> WHERE `id` > 100;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> SELECT `id`
    -> FROM `tbl_test`;
+------+
| id   |
+------+
|  101 |
|  102 |
+------+
2 rows in set (0.00 sec)

mysql> INSERT INTO `tbl_test`
    -> SELECT `id` + 1
    -> FROM `tbl_test`
    -> WHERE `id` < 100;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> SELECT `id`
    -> FROM `tbl_test`;
+------+
| id   |
+------+
|  101 |
|  102 |
+------+
2 rows in set (0.00 sec)

请参阅db-fiddle。

Answer 2

您可以使用INSERT IGNORE INTO解决您的问题。

例如：

INSERT IGNORE INTO A (x, y, created_at) 
(SELECT x, "something", a_timestamp 
FROM B WHERE c IS NULL AND a_timestamp > NOW())

可以找到更多信息here

Answer 3

   private void btnSrcDataID_Click(object sender, EventArgs e)
        {
            try
             {
                dgvInsertInfo.Refresh();

                SqlComm.Connection = SqlConn;

                String sqlQueryString = ("SELECT * FROM MyDataTable WHERE      
                DataID=@DataID");
                SqlComm.Parameters.AddWithValue("@DataID", txtDataID.Text);

                SqlComm = new SqlCommand(sqlQueryString, SqlConn);
                SqlDataTable = new DataTable();

                SqlAdapt = new SqlDataAdapter(SqlComm);

                DataSet dsQryDataId = new DataSet();
                SqlAdapt.Fill(dsQryDataId);

            //Passing data to DatagridView
                dgvInsertInfo.DataSource = dsQryDataId;

            }
             catch (Exception ex)
              {
                 MessageBox.Show(ex.Message);
              }
          }

要

"INSERT INTO A (x, y, created_at) 
(SELECT x, \"something\", a_timestamp 
FROM B WHERE c IS NULL AND a_timestamp > \"#{current_time}\")

使用SELECT的空结果INSERT INTO

3 个答案: