litsql - Literal SQL query builder

litsql is a Golang string concatenation library disguised as an SQL query builder.

Ok, it really is an SQL query builder, but it aims to be an easier-to-use replacement for raw SQL strings.

Each litsql statement must be directly related to an SQL output, including whitespace (backed by whitespace tests), which must be obvious to the user of the library. The output will be exactly the passed values.

func ExampleSelect_literalSimple() {
    // SELECT
    q := psql.Select(
        // u.id, u.name
        sm.Columns("u.id", "u.name"),
        // , u.created_at, u.updated_at
        sm.Columns("u.created_at", "u.updated_at"),
        // FROM users AS u
        sm.From("users AS u"),
        // WHERE u.age > $1
        sm.WhereClause("u.age > ?", 40),
        // WHERE u.city_id = $2
        sm.WhereClause("u.city_id = ?", sq.NamedArg("city_id")),
        // AND u.deleted_at IS NOT NULL
        sm.Where("u.deleted_at IS NOT NULL"),
        // ORDER BY u.name ASC, u.age DESC
        sm.OrderBy("u.name ASC", "u.age DESC"),
    )
    qs, args, err := q.Build(
        sq.WithParseArgs(sq.MapArgValues{
            "city_id": 66,
        }),
    )
    if err != nil {
        panic(err)
    }
    fmt.Println(qs)
    fmt.Println("===")
    fmt.Println(args)

    // Output:
    // SELECT u.id, u.name, u.created_at, u.updated_at
    // FROM users AS u
    // WHERE u.age > $1 AND u.city_id = $2 AND u.deleted_at IS NOT NULL
    // ORDER BY u.name ASC, u.age DESC
    // ===
    // [40 66]
}

This library will do:

• ensure clause ordering
• enforce some kind of code structure
• be type-safe without using any too much
• guarantee whitespace. extra whitespace is considered a bug
• output correct argument characters for each database dialect

This library won't do:

• prevent invalid SQL from being output
• quoting
• execute queries in databases
• provide helper expressions to build things like "IsEQ()", "Not(expression)", "LT(value)". These are expected to be written as strings
• be an ORM (never)

The different SQL dialects uses code generation to add/remove things that are dialect specific.

Installation

go get -u github.com/rrgmc/litsql

Reference

This library is heavily inspired by the excellent Bob Go SQL Access Toolkit. Its base ideas and some of its implementations where used to build this library.

The biggest difference is that Bob is not only a query builder, but an ORM, so the query builder part must be much more complex to be able to tackle multiple jobs. It encourages using Go to code SQL expressions, which this library heavily discourages.

Dialects

• PostgreSQL
• MySQL
• SQLite

Related

• libsql-db: wrappers for running litsql queries directly in databases.

Examples

func ExampleSelect_literalJoin() {
    // SELECT
    q := psql.Select(
        // orders.id as order_id, orders.date
        sm.Columns("orders.id AS order_id", "orders.date"),
        // u.id AS user_id, u.name as user_name
        sm.Columns("u.id AS user_id", "u.name AS user_name"),
        // FROM orders
        sm.From("orders"),
        // INNER JOIN users AS u ON orders.user_id = u.id
        sm.InnerJoin("users AS u").On("orders.user_id = u.id"),
        // WHERE u.age > $1
        sm.WhereClause("u.age ?",
            // example to use either IS NULL or a comparison
            expr.IfElse(true, // some condition
                expr.Clause("> ?", 32),
                expr.String("IS NULL"))),
        // AND u.deleted_at IS NOT NULL
        sm.Where("u.deleted_at IS NOT NULL"),
        // ORDER BY order.date DESC, u.name ASC
        sm.OrderBy("orders.date DESC", "u.name ASC"),
    )
    qs, args, err := q.Build()
    if err != nil {
        panic(err)
    }
    fmt.Println(qs)
    fmt.Println("===")
    fmt.Println(args)

    // Output:
    // SELECT orders.id AS order_id, orders.date, u.id AS user_id, u.name AS user_name
    // FROM orders
    // INNER JOIN users AS u ON orders.user_id = u.id
    // WHERE u.age > $1 AND u.deleted_at IS NOT NULL
    // ORDER BY orders.date DESC, u.name ASC
    // ===
    // [32]
}

func ExampleSelect_literalWith() {
    q := psql.Select(
        // WITH regional_sales AS (
        sm.With("regional_sales").As(
            // SELECT
            psql.Select(
                // region, SUM(amount) AS total_sales
                sm.Columns("region", "SUM(amount) AS total_sales"),
                // FROM orders
                sm.From("orders"),
                // GROUP BY region
                sm.GroupBy("region"),
            ),
        ),
        // ), top_regions AS (
        sm.With("top_regions").As(
            // SELECT
            psql.Select(
                // region
                sm.Columns("region"),
                // FROM regional_sales
                sm.From("regional_sales"),
                // WHERE total_sales > (SELECT SUM(total_sales)/10 FROM regional_sales)
                sm.WhereClause("total_sales > ?",
                    psql.Select(
                        sm.Columns("SUM(total_sales)/10"),
                        sm.From("regional_sales"),
                    ),
                ),
            ),
        ),
        // )
        // SELECT
        // region, product, SUM(quantity) AS product_units, SUM(amount) AS product_sales
        sm.Columns("region", "product", "SUM(quantity) AS product_units", "SUM(amount) AS product_sales"),
        // FROM orders
        sm.From("orders"),
        // WHERE region IN (SELECT region FROM top_regions)
        sm.WhereClause("region IN ?",
            psql.Select(
                sm.Columns("region"),
                sm.From("top_regions"),
            ),
        ),
        // GROUP BY region, product
        sm.GroupBy("region", "product"),
    )
    qs, _, err := q.Build()
    if err != nil {
        panic(err)
    }
    fmt.Println(qs)

    // Output:
    // WITH regional_sales AS (
    //   SELECT region, SUM(amount) AS total_sales
    //   FROM orders
    //   GROUP BY region
    // ),
    // top_regions AS (
    //   SELECT region
    //   FROM regional_sales
    //   WHERE total_sales > (
    //     SELECT SUM(total_sales)/10
    //     FROM regional_sales
    //   )
    // )
    // SELECT region, product, SUM(quantity) AS product_units, SUM(amount) AS product_sales
    // FROM orders
    // WHERE region IN (
    //   SELECT region
    //   FROM top_regions
    // )
    // GROUP BY region, product
}

Tasks

Dynamic query building

type userFilter struct {
    Name string
}
filter := userFilter{
    Name: "john",
}
query := psql.Select(
    sm.Columns("id", "name"),
    sm.From("users"),
)
if filter.Name != "" {
    query.Apply(
        sm.WhereClause("name = ?", filter.Name),
    )
}

Select from subselect

query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.FromQuery(psql.Select(
        sm.Columns("id", "name", "age"),
        sm.From("users"),
        sm.Where("age > 10"),
    )),
)

SELECT id, name, age
FROM (
  SELECT id, name, age
  FROM users
  WHERE age > 10
)

WHERE value IN

query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.From("users"),
    sm.WhereClause("age IN (?)", expr.In([]any{15, 30, 45})),
)

SELECT id, name, age
FROM users
WHERE age IN ($1, $2, $3)

--------------- QUERY ARGS ---------------
([]interface {}) (len=3 cap=3) {
 (int) 15,
 (int) 30,
 (int) 45
}

WHERE value IN using named arguments

query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.From("users"),
    sm.WhereClause("age IN (?)", expr.In([]any{
        sq.NamedArg("first"),
        sq.NamedArg("second"),
        sq.NamedArg("third"),
    })),
)
qs, args, err := query.Build(
    sq.WithParseArgs(sq.MapArgValues{
        "first":  15,
        "second": 30,
        "third":  45,
    }),
)

SELECT id, name, age
FROM users
WHERE age IN ($1, $2, $3)

+++++++++++++++ PARSED ARGS +++++++++++++++
([]interface {}) (len=3 cap=4) {
 (int) 15,
 (int) 30,
 (int) 45
}

WHERE value IN subselect

query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.From("users"),
    sm.WhereClause("region IN ?",
        psql.Select(
            sm.Columns("region"),
            sm.From("top_regions"),
        ),
    ),
)

SELECT id, name, age
FROM users
WHERE region IN (
  SELECT region
  FROM top_regions
)

Expression function to generate using custom code

query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.From("users"),
    sm.WhereClause("age > ?",
        expr.Func(func() (litsql.Expression, error) {
            r := rand.Intn(3)
            switch r {
            case 0:
                return expr.Arg(20), nil
            case 1:
                return expr.Arg(30), nil
            default:
                return expr.Arg(50), nil
            }
        }),
    ),
)

SELECT id, name, age
FROM users
WHERE age > $1

--------------- QUERY ARGS ---------------
([]interface {}) (len=1 cap=1) {
 (int) 30
}

Add clauses in inline callback

query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.From("users"),
    sm.Apply(func(a psql.SelectModApply) {
        a.Apply(
            sm.Where("age > 10"),
        )
    }),
)

SELECT id, name, age
FROM users
WHERE age > 10

Use IS NULL or a condition depending on a flag

v := any(32)
query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.From("users"),
    sm.WhereClause("u.age ?",
        expr.IfElse(v != nil,
            expr.Clause("> ?", 32),
            expr.String("IS NULL"))),
)

SELECT id, name, age
FROM users
WHERE u.age > $1

--------------- QUERY ARGS ---------------
([]interface {}) (len=1 cap=1) {
 (int) 32
}

OR expression

query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.From("users"),
    sm.WhereExpr(
        expr.OrExpr(
            expr.Clause("(age > ? AND city_id = ?)", 10, 12),
            expr.Clause("(age < ? AND city_id = ?)", 10, 15),
        ),
    ),
)

SELECT id, name, age
FROM users
WHERE (age > $1 AND city_id = $2) OR (age < $3 AND city_id = $4)

([]interface {}) (len=4 cap=4) {
 (int) 10,
 (int) 12,
 (int) 10,
 (int) 15
}

UNION

query := psql.Select(
    sm.Columns("id", "name", "age"),
    sm.From("users"),
    sm.Where("age < 10"),
    sm.Union(psql.Select(
        sm.Columns("id", "name", "age"),
        sm.From("users"),
        sm.Where("age > 50"),
    )),
)

SELECT id, name, age
FROM users
WHERE age < 10
UNION (
  SELECT id, name, age
  FROM users
  WHERE age > 50
)

Full raw query (the query and parameters will be returned as-is)

query := psql.SelectRaw("select * from users where user_id = $1", 55)

select * from users where user_id = $1

([]interface {}) (len=1 cap=1) {
 (int) 55
}

Full raw query (with clause processing)

query := psql.SelectRawExpr(expr.Clause("select * from users where user_id = ?", 55))

select * from users where user_id = $1

--------------- QUERY ARGS ---------------
([]interface {}) (len=1 cap=1) {
 (int) 55
}

Prepared statements

When using prepared statements, the use of named arguments is required, as it would be impossible to know which argument maps to each value.

query := psql.Select(
    sm.Columns("film_id", "title", "length"),
    sm.From("film"),
    sm.WhereClause("length > ?", sq.NamedArg("length")),
    sm.LimitArgNamed("limit"),
)

queryStr, args, err := query.Build()
if err != nil {
    return err
}

prepq, err := db.PrepareContext(ctx, queryStr)
if err != nil {
    return err
}

pargs, err := sq.ParseArgs(args, map[string]any{
    "length": 100,
    "limit":  10,
})
if err != nil {
    return err
}

rows, err := prepq.QueryContext(ctx, pargs...)
if err != nil {
    return err
}
defer rows.Close()

for rows.Next() {
    var id, length int
    var title string
    if err := rows.Scan(&id, &title, &length); err != nil {
        return err
    }
    fmt.Println(id, title, length)
}

if rows.Err() != nil {
    return rows.Err()
}

Author

Rangel Reale ([email protected])