GO Conn.ExecContext用法及代码示例

package main

import (
    "context"
    "database/sql"
    "log"
)

var (
    ctx context.Context
    db  *sql.DB
)

func main() {
    // A *DB is a pool of connections. Call Conn to reserve a connection for
    // exclusive use.
    conn, err := db.Conn(ctx)
    if err != nil {
        log.Fatal(err)
    }
    defer conn.Close() // Return the connection to the pool.
    id := 41
    result, err := conn.ExecContext(ctx, `UPDATE balances SET balance = balance + 10 WHERE user_id = ?;`, id)
    if err != nil {
        log.Fatal(err)
    }
    rows, err := result.RowsAffected()
    if err != nil {
        log.Fatal(err)
    }
    if rows != 1 {
        log.Fatalf("expected single row affected, got %d rows affected", rows)
    }
}