How to connect to a SQL database (MySQL/PostgreSQL) in Go?
Jul 24, 2025 am 04:05 AM
When connecting to SQL databases in Go, you need to pay attention to driver registration, DSN format and basic operation procedures. 1. Install the driver package of the corresponding database, such as MySQL uses github.com/go-sql-driver/mysql, PostgreSQL uses github.com/lib/pq; 2. Use the database/sql interface and import the driver, configure the connection through the sql.Open function, but the actual connection is only established when Ping() is called; 3. The DSN format must be correct, the MySQL example is user:password@tcp(127.0.0.1:3306)/dbname, and the PostgreSQL example is user=postgres password=secret dbname=testdb sslmode=disable; 4. Query is used, insert or update is used to use Exec, and pay attention to parameterized placeholder differences, use MySQL for?, PostgreSQL for $1, $2, etc.; 5. After the operation is completed, be sure to close the rows and db connections to avoid resource leakage.
Connecting to a SQL database (such as MySQL or PostgreSQL) is actually not difficult in Go, but you should pay attention to several key points: driver registration, connection string format, and basic processes for database operations. Let’s talk about how to do it.
Install the necessary driver package
Go itself does not have a built-in database driver, and the corresponding driver needs to be installed according to the type of database you want to connect to. Common ones are:
- MySQL:
github.com/go-sql-driver/mysql - PostgreSQL:
github.com/lib/pq
You can install these dependencies through the go get command:
go get -u github.com/go-sql-driver/mysql go get -u github.com/lib/pq
Note: Even if you only use one of the databases, make sure to import the correct driver package, otherwise an error will be reported and the driver cannot be found.
Use database/sql interface to connect to the database
Go provides the standard interface database/sql to handle SQL databases. You need to import it first and then add a specific driver package.
Example of connecting to MySQL:
import (
"database/sql"
_ "github.com/go-sql-driver/mysql"
)
func main() {
dsn := "user:password@tcp(127.0.0.1:3306)/dbname"
db, err := sql.Open("mysql", dsn)
if err != nil {
panic(err)
}
defer db.Close()
// Test whether the connection is successful err = db.Ping()
if err != nil {
panic(err)
}
}Example of connecting to PostgreSQL:
import (
"database/sql"
_ "github.com/lib/pq"
)
func main() {
connStr := "user=postgres password=secret dbname=testdb sslmode=disable"
db, err := sql.Open("postgres", connStr)
if err != nil {
panic(err)
}
defer db.Close()
err = db.Ping()
if err != nil {
panic(err)
}
}A few explanations:
- The DSN (Data Source Name) format is very important. Different database formats are different. If you write it incorrectly, you can't even go.
-
_is used to trigger the driver's init function to register itself forsql.DB -
sql.Opendoes not make connections immediately, it is just configured. The real connection only occurs in subsequent operations (such asPing()).
Process query and execution statements
Once the connection is successful, you can start performing SQL operations.
A common practice is to use Query to query data, or use Exec to execute insert, update and other statements.
For example query:
rows, err := db.Query("SELECT id, name FROM users")
if err != nil {
panic(err)
}
defer rows.Close()
for rows.Next() {
var id int
var name string
err = rows.Scan(&id, &name)
if err != nil {
panic(err)
}
fmt.Println(id, name)
}Example of inserting data:
result, err := db.Exec("INSERT INTO users (name) VALUES (?)", "Alice")
if err != nil {
panic(err)
}
lastId, _ := result.LastInsertId()
fmt.Println("Inserted ID:", lastId)Notes:
- Remember to close rows, otherwise resources may be leaked.
- Parameterized queries prevent SQL injection.
- Different database placeholders are different, what is MySQL
?PostgreSQL is$1,$2, etc.
Basically that's it. Just pay attention to the driver, DSN format and basic database operation methods, and you can connect and operate MySQL or PostgreSQL smoothly.
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