I want to retreive rows from SQL table1, table 2, table3 and want to store it in a table4 in C# using mysql

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 public void getdata()
     {
      try
      {
      using (MySqlCommand cmd = new MySqlCommand("SELECT * FROM aa", con))
       {
      cmd.CommandType = CommandType.Text;
      using (MySqlDataAdapter sda = new MySqlDataAdapter(cmd))
        {
     using (DataTable dt = new DataTable())
     {
     sda.Fill(dt);

   for (int i = 0; i < dt.Rows.Count; i++)
   {
   id =(string) dt.Rows[i]["id"];
    }

        // String query = "insert into nok_data_log(ID,Date_,Primary_Barcode,Station1_Status,Station2_Status,Station3_Status,Station4_Status,Station5_Status,Station6_Status,Station7_Status,Station8_Status,Station9_Status,Station1_Bcd1,Station1_Bcd2,Station1_Bcd3,Station2_Bcd1,Station2_Bcd2,Station2_Bcd3,Station3_Bcd1,Station3_Bcd2,Station3_Bcd3,Station4_Bcd1,Station4_Bcd2,Station4_Bcd3,Station5_Bcd1,Station5_Bcd2,Station5_Bcd3,Station6_Bcd1,Station6_Bcd2,Station6_Bcd3,Station7_Bcd1,Station7_Bcd2,Station7_Bcd3,Station8_Bcd1,Station8_Bcd2,Station8_Bcd3,Station9_Bcd1,Station9_Bcd2,Station9_Bcd3) values(@ID, @Date_, @Primary_Barcode, @Station1_Status,@Station2_Status,@Station3_Status,@Station4_Status,@Station5_Status,@Station6_Status,@Station7_Status,@Station8_Status, @Station9_Status, @Station1_Bcd1, @Station1_Bcd2, @Station1_Bcd3, @Station2_Bcd1, @Station2_Bcd2, @Station2_Bcd3, @Station3_Bcd1, @Station3_Bcd2, @Station3_Bcd3, @Station4_Bcd1, @Station4_Bcd2, @Station4_Bcd3, @Station5_Bcd1, @Station5_Bcd2, @Station5_Bcd3, @Station6_Bcd1, @Station6_Bcd2, @Station6_Bcd3,@Station7_Bcd1,@Station7_Bcd2,@Station7_Bcd3,@Station8_Bcd1,@Station8_Bcd2, @Station8_Bcd3,@Station9_Bcd1,@Station9_Bcd1,@Station9_Bcd1)";
 string query = "insert into bb(id,name)values (@id, @name)";

                        }
                    }
                }
}
            catch (Exception ex)
            {
                LogFileWrite("getdata,frmAuto : " + ex.Message);
            }
        }

What I have tried:

INSERT and DELETE in single operation (moving from one table to other in c# using mysql)

eg.
i have a table table1, table record ,save in another table table2
& delete record from table1 create c# function winform
actually can't understood how to solve plz help

Thanks in advance!

Posted 12-Mar-21 23:51pm

Member 11893460

Updated 13-Mar-21 1:58am

v2

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Maciej Los · Answer 1 · 2021-03-13T01:58:00

The way you're trying to do it is completely wrong!

You should avoid of copying data row-by-row (record-by-record), due to tons of reasons.

If the structure of tables is the same, you can use INSERT INTO[^]:

SQL

INSERT INTO Table4 (Field1, Field2, ... FieldN)
SELECT Field1, Field2, ... FieldN
FROM (
  SELECT Field1, Field2, ... FieldN
  FROM Table1
  UNION ALL
  SELECT Field1, Field2, ... FieldN
  FROM Table2
  UNION ALL
  SELECT Field1, Field2, ... FieldN
  FROM Table3
) A

In case you need to get data from 3 tables and they are related, you need to use JOIN:

SQL

INSERT INTO Table4 (Field1, Field2, ... FieldN)
SELECT Field1, Field2, ... FieldN
FROM (
  SELECT t1.Field1, t2.Field2, ... t3.FieldN
  FROM Table1 t1 
    INNER|OUTER|LEFT|RIGHT JOIN Table2 t2 ON t1.PrimaryKey = t2.ForeignKey
    INNER|OUTER|LEFT|RIGHT JOIN Table3 t3 ON t2.PrimaryKey = t3.ForeignKey
) A

For further details, please see: Visual Representation of SQL Joins[^]