I saw this example from sqlite3
on GitHub
:
import (
"database/sql"
"fmt"
_ "github.com/mattn/go-sqlite3"
"log"
"os"
)
and cannot seem to find what the underscore in front of an import statement means.
It's for importing a package solely for its side-effects.
From the Go Specification:
To import a package solely for its side-effects (initialization), use the blank identifier as explicit package name:
import _ "lib/math"
In the case of go-sqlite3, the underscore import is used for the side-effect of registering the sqlite3
driver as a database driver in the init()
function, without importing any other functions:
sql.Register("sqlite3", &SQLiteDriver{})
Once it's registered in this way, sqlite3 can be used with the standard library's sql
interface in your code like in the example:
db, err := sql.Open("sqlite3", "./foo.db")