golang的mysql组件包sqlx
sqlx is a library which provides a set of extensions on go's standard database/sql library. The sqlx versions of sql.DB, sql.TX, sql.Stmt, et al. all leave the underlying interfaces untouched, so that their interfaces are a superset on the standard ones. This makes it relatively painless to integrate existing codebases using database/sql with sqlx.
Major additional concepts are:
Marshal rows into structs (with embedded struct support), maps, and slices
Named parameter support including prepared statements
Get and Select to go quickly from query to struct/slice
In addition to the godoc API documentation, there is also some standard documentation that explains how to use database/sql along with sqlx.
Recent Changes
sqlx/types.JsonText has been renamed to JSONText to follow Go naming conventions.
This breaks backwards compatibility, but it's in a way that is trivially fixable (s/JsonText/JSONText/g). The types package is both experimental and not in active development currently.
Using Go 1.6 and below with types.JSONText and types.GzippedText can be potentially unsafe, especially when used with common auto-scan sqlx idioms like Select and Get. See golang bug #13905.
Backwards Compatibility
There is no Go1-like promise of absolute stability, but I take the issue seriously and will maintain the library in a compatible state unless vital bugs prevent me from doing so. Since #59 and #60 necessitated breaking behavior, a wider API cleanup was done at the time of fixing. It's possible this will happen in future; if it does, a git tag will be provided for users requiring the old behavior to continue to use it until such a time as they can migrate.
install
go get github.com/jmoiron/sqlx
issues
Row headers can be ambiguous (SELECT 1 AS a, 2 AS a), and the result of Columns() does not fully qualify column names in queries like:
SELECT a.id, a.name, b.id, b.name FROM foos AS a JOIN foos AS b ON a.parent = b.id;
making a struct or map destination ambiguous. Use AS in your queries to give columns distinct names, rows.Scan to scan them manually, or SliceScan to get a slice of results.
usage
Below is an example which shows some common use cases for sqlx. Check sqlx_test.go for more usage.
package main
import (
_ "github.com/lib/pq"
"database/sql"
"github.com/jmoiron/sqlx"
"log"
)
var schema = `
CREATE TABLE person (
first_name text,
last_name text,
email text
);
CREATE TABLE place (
country text,
city text NULL,
telcode integer
)`
type Person struct {
FirstName string `db:"first_name"`
LastName string `db:"last_name"`
Email string
}
type Place struct {
Country string
City sql.NullString
TelCode int
}
func main() {
// this Pings the database trying to connect, panics on error
// use sqlx.Open() for sql.Open() semantics
db, err := sqlx.Connect("postgres", "user=foo dbname=bar sslmode=disable")
if err != nil {
log.Fatalln(err)
}
// exec the schema or fail; multi-statement Exec behavior varies between
// database drivers; pq will exec them all, sqlite3 won't, ymmv
db.MustExec(schema)
tx := db.MustBegin()
tx.MustExec("INSERT INTO person (first_name, last_name, email) VALUES ($1, $2, $3)", "Jason", "Moiron", "jmoiron@jmoiron.net")
tx.MustExec("INSERT INTO person (first_name, last_name, email) VALUES ($1, $2, $3)", "John", "Doe", "johndoeDNE@gmail.net")
tx.MustExec("INSERT INTO place (country, city, telcode) VALUES ($1, $2, $3)", "United States", "New York", "1")
tx.MustExec("INSERT INTO place (country, telcode) VALUES ($1, $2)", "Hong Kong", "852")
tx.MustExec("INSERT INTO place (country, telcode) VALUES ($1, $2)", "Singapore", "65")
// Named queries can use structs, so if you have an existing struct (i.e. person := &Person{}) that you have populated, you can pass it in as &person
tx.NamedExec("INSERT INTO person (first_name, last_name, email) VALUES (:first_name, :last_name, :email)", &Person{"Jane", "Citizen", "jane.citzen@example.com"})
tx.Commit()
// Query the database, storing results in a []Person (wrapped in []interface{})
people := []Person{}
db.Select(&people, "SELECT * FROM person ORDER BY first_name ASC")
jason, john := people[0], people[1]
fmt.Printf("%#v\n%#v", jason, john)
// Person{FirstName:"Jason", LastName:"Moiron", Email:"jmoiron@jmoiron.net"}
// Person{FirstName:"John", LastName:"Doe", Email:"johndoeDNE@gmail.net"}
// You can also get a single result, a la QueryRow
jason = Person{}
err = db.Get(&jason, "SELECT * FROM person WHERE first_name=$1", "Jason")
fmt.Printf("%#v\n", jason)
// Person{FirstName:"Jason", LastName:"Moiron", Email:"jmoiron@jmoiron.net"}
// if you have null fields and use SELECT *, you must use sql.Null* in your struct
places := []Place{}
err = db.Select(&places, "SELECT * FROM place ORDER BY telcode ASC")
if err != nil {
fmt.Println(err)
return
}
usa, singsing, honkers := places[0], places[1], places[2]
fmt.Printf("%#v\n%#v\n%#v\n", usa, singsing, honkers)
// Place{Country:"United States", City:sql.NullString{String:"New York", Valid:true}, TelCode:1}
// Place{Country:"Singapore", City:sql.NullString{String:"", Valid:false}, TelCode:65}
// Place{Country:"Hong Kong", City:sql.NullString{String:"", Valid:false}, TelCode:852}
// Loop through rows using only one struct
place := Place{}
rows, err := db.Queryx("SELECT * FROM place")
for rows.Next() {
err := rows.StructScan(&place)
if err != nil {
log.Fatalln(err)
}
fmt.Printf("%#v\n", place)
}
// Place{Country:"United States", City:sql.NullString{String:"New York", Valid:true}, TelCode:1}
// Place{Country:"Hong Kong", City:sql.NullString{String:"", Valid:false}, TelCode:852}
// Place{Country:"Singapore", City:sql.NullString{String:"", Valid:false}, TelCode:65}
// Named queries, using `:name` as the bindvar. Automatic bindvar support
// which takes into account the dbtype based on the driverName on sqlx.Open/Connect
_, err = db.NamedExec(`INSERT INTO person (first_name,last_name,email) VALUES (:first,:last,:email)`,
map[string]interface{}{
"first": "Bin",
"last": "Smuth",
"email": "bensmith@allblacks.nz",
})
// Selects Mr. Smith from the database
rows, err = db.NamedQuery(`SELECT * FROM person WHERE first_name=:fn`, map[string]interface{}{"fn": "Bin"})
// Named queries can also use structs. Their bind names follow the same rules
// as the name -> db mapping, so struct fields are lowercased and the `db` tag
// is taken into consideration.
rows, err = db.NamedQuery(`SELECT * FROM person WHERE first_name=:first_name`, jason)
}
