Question

I am confused about this query where it uses insert statement and then ignore and then select. Can someone explain me this? Thanks

INSERT IGNORE INTO
        myTable
    SELECT
        $var1  AS `CMMNCTID`,
        $var2  AS `ENCID`,
        variableID,
        ProductID,
        CustomerID,
        Age,
        "" AS `myJ`,
        "" AS `myI`
    FROM
        table2
    JOIN
        table3
    ON
        table2.ID= table3.ID

Answer 1

The SELECT is a subquery. What the INSERT is doing is inserting whatever is contained in the join of table2 and table3, into myTable. The IGNORE tells it to ignore any entries for keys that already exist in myTable and to just insert whatever doesn’t yet exist.

It seems the purpose of the query is to combine the data that is associated between table2 and table3 and dump it into myTable.