Go SQL: When to Use `DB.Exec()`, `DB.Query()`, and Prepared Statements?

Why even use *DB.exec() or prepared statements in Golang?

The Go SQL package provides methods for executing SQL statements. There are two main methods: DB.Exec() and DB.Query().

DB.Exec() is used to execute SQL statements that do not return any rows, such as INSERT, UPDATE, and DELETE statements. DB.Query() is used to execute SQL statements that return rows, such as SELECT statements.

The book you're citing states that "If a function name includes Query, it is designed to ask a question of the database, and will return a set of rows, even if it’s empty. Statements that don’t return rows should not use Query functions; they should use Exec()."

This is true, but it's not the whole story. DB.Exec() can also be used to execute SQL statements that return rows. However, DB.Exec() will return the number of rows affected by the statement, while DB.Query() will return a *Rows object that can be used to iterate over the rows in the result set.

So, when should you use DB.Exec() and when should you use DB.Query()?

Use DB.Exec() when you need to execute a SQL statement that does not return any rows and you want to know the number of rows affected by the statement.

Use DB.Query() when you need to execute a SQL statement that returns rows and you want to iterate over the rows in the result set.

Why use prepared statements?

Prepared statements can improve the performance of your SQL queries. When you prepare a statement, the database server compiles the statement and stores the compiled statement in memory. This means that the database server does not have to recompile the statement every time you execute it.

To use prepared statements, you can call the DB.Prepare() method. This method takes a SQL statement as an argument and returns a *Stmt object. You can then execute the prepared statement by calling the Stmt.Exec() or Stmt.Query() method.

Whether or not you should use prepared statements depends on the performance characteristics of your application. If you're executing the same SQL statement multiple times, then using a prepared statement can improve the performance of your application.

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