CODEWITHSUNDEEP
sqlgotransactions
Jake Muller
Jake Muller

Reputation: 1063

What are the differences between QueryRow and Exec in Golang SQL package?

In Golang SQL package there are QueryRow and Exec for executing query. If I'm executing insertion query inside transaction, which is better to be used in term of performance?

err = tx.QueryRow(query, params).Scan(&id)

vs

result, err = tx.Exec(query, params)

Upvotes: 9

Views: 8449

Answers (2)

topenion
topenion

Reputation: 460

Generally for reading 1 row use QueryRow()

err := tx.QueryRow(`Select col from t where col=$1`, "val").Scan(&colholder)

For manipulating data via UPDATE, DELETE, INSERT etc. Use Exec

result, err := tx.Exec(`Delete from t where col=$1`, "val")

As you can see there is nothing to scan in Exec because that is execution and not query.

However no one is stopping you from QueryRow for Exec operation, or vice versa but it will not be intended purpose. You might lose under the hood optimization for each type of operation. Also if you use QueryRow for Exec, you will get sql.ErrNoRows error because there is no row to return in UPDATE, INSERT or DELETE.

Similarly you will not be able to get value from Exec as it returns response which can not be .Scanned, if you use query operation in Exec.

However there are cases for using QueryRow for Exec operations

err := tx.QueryRow(`Delete from t where col=$1 returning id`, "val").Scan(&deletedID)

You just decide if you want a return value from sql operation, use QueryRow else use Exec.

In your case if you want some data back like id after insert operation use QueryRow, otherwise Exec suits just fine.

Upvotes: 17

colm.anseo
colm.anseo

Reputation: 22117

If you're inserting a single row use QueryRow - it is designed for, at most, one row update.

If you are performing multi-command updates/queries with multiple results, use Exec. The row results from Exec need to be closed after row iteration has completed.

So for ease of use & if you know you're only manipulating one row, go with QueryRow.

Upvotes: 4

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