How to Efficiently Count Database Rows in Go?

Counting Database Rows in Go

When working with databases in Go, it's often necessary to determine the number of rows in a table. This information can be useful for pagination, statistics, and other purposes.

The most straightforward way to count rows in Go is using the Query function:

<code class="go">count, err := db.Query("SELECT COUNT(*) FROM main_table")</code>

However, Query returns a *sql.Rows object, which represents a result set. To retrieve the actual row count, you need to read this result set into a variable using the Scan function:

<code class="go">rows, err := db.Query("SELECT COUNT(*) FROM main_table")
if err != nil {
    log.Fatal(err)
}
defer rows.Close()

var count int

for rows.Next() {   
    if err := rows.Scan(&count); err != nil {
        log.Fatal(err)
    }
}

fmt.Printf("Number of rows are %s\n", count)</code>

Note that you should always defer closing the *sql.Rows object to release its resources.

A more efficient alternative to Query for retrieving a single row count is the QueryRow function:

<code class="go">var count int

err := db.QueryRow("SELECT COUNT(*) FROM main_table").Scan(&count)
switch {    
case err != nil:
    log.Fatal(err)
default:
    fmt.Printf("Number of rows are %s\n", count)
}</code>

QueryRow is designed specifically for retrieving a single row, avoiding the need to iterate over a result set.

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