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Result: column "pettypeid" specified more than once In my case, the foreign keys share the same names as their primary key counterparts in the parent table, and I would have received an error due to duplicate column names being created in the destination table. Specifically, I didn’t want to double up on the foreign key/ primary key columns. Note that I listed out each column here because I didn’t want to include all columns. Here, we query three tables and insert the results into a table called PetsTypesOwners. You can select data from multiple tables, then have the destination table’s definition be based on the result set. In this example, I filter the data to just those pets who have a date of birth (DOB) from before the 1st of June, 2020. The SELECT statement can do the usual SELECT statement stuff, such as filtering the results with a WHERE clause. That is, it will add new rows to the table, while keeping any existing rows. This will append the data to any existing data. If you want to insert data into a table that already exists, use the INSERT INTO. AS SELECT statement again, we get an error, due to the table already existing. Petid | pettypeid | ownerid | petname | dob If we select both tables, we can see they both have the same data. The SQL standard requires parentheses around the subquery clause, but they may be optional in your DBMS (for example PostgreSQL). However, it doesn’t include indexes and other column attributes. This creates a new table called Pets2 (with the same columns as Pets), and inserts the query results into it. Here’s a basic example to demonstrate selecting and inserting the data into a new table. AS SELECT statement enables you to insert the results of a query into a new table.
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