Documentation
¶
Overview ¶
Package dialect spells the parts of SQL that differ between engines.
Everything here returns a fragment of SQL text, so a caller composes with it the same way it composes with any other string and never branches on the engine itself. A caller that finds itself writing "if postgres" has found a spelling that belongs in this package.
The fragments assume the loose typing that both SQLite and Postgres allow for a column declared to hold JSON: the value may be a JSON array, or a bare scalar that should read as a one-element array. Each JSON fragment normalizes that before it does anything else, so Dialect.Each over a column holding "abc" yields one row, not an error.
Index ¶
- type Dialect
- type Postgres
- func (Postgres) Array(expr string) string
- func (Postgres) Bool(v bool) string
- func (Postgres) Bytes() string
- func (Postgres) Catalog() string
- func (Postgres) Checkpoint() string
- func (Postgres) Columns() string
- func (d Postgres) Each(expr string) string
- func (Postgres) Extract(expr, path string) string
- func (Postgres) Format() string
- func (Postgres) Json() string
- func (d Postgres) Last(expr string) string
- func (Postgres) Length(expr string) string
- func (Postgres) Like() string
- func (Postgres) Name() string
- func (Postgres) Now() string
- func (Postgres) Number(expr string) string
- func (Postgres) Optimize() string
- func (Postgres) Prelude() string
- func (Postgres) Quote(name string) string
- func (Postgres) Random(n int) string
- func (Postgres) Row() string
- type SQLite
- func (SQLite) Array(expr string) string
- func (SQLite) Bool(v bool) string
- func (SQLite) Bytes() string
- func (SQLite) Catalog() string
- func (SQLite) Checkpoint() string
- func (SQLite) Columns() string
- func (d SQLite) Each(expr string) string
- func (SQLite) Extract(expr, path string) string
- func (SQLite) Format() string
- func (SQLite) Json() string
- func (d SQLite) Last(expr string) string
- func (SQLite) Length(expr string) string
- func (SQLite) Like() string
- func (SQLite) Name() string
- func (SQLite) Now() string
- func (SQLite) Number(expr string) string
- func (SQLite) Optimize() string
- func (SQLite) Prelude() string
- func (SQLite) Quote(name string) string
- func (SQLite) Random(n int) string
- func (SQLite) Row() string
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Dialect ¶
type Dialect interface {
// Name is the engine, "sqlite" or "postgres".
Name() string
// Quote wraps an identifier so it survives a keyword collision or an
// uppercase letter.
Quote(name string) string
// Now is the current UTC instant in Base's stored layout,
// 2006-01-02 15:04:05.000Z.
Now() string
// Random is n lowercase hexadecimal characters. n must be even.
Random(n int) string
// Json is the column type for a value holding JSON.
Json() string
// Bytes is the column type for a value holding opaque binary.
Bytes() string
// Like is the operator matching a value against a pattern without regard
// to case, so one filter selects the same rows on either engine.
Like() string
// Bool is the literal for a truth value.
Bool(v bool) string
// Number reads expr — a value read out of a JSON document, which arrives
// as text whatever the document held — as a number, for an engine that
// compares a number only to a number. Text that is not a numeral reads as
// null, so comparing it to a number is false rather than an error.
Number(expr string) string
// Array reads expr as a JSON array, wrapping a bare scalar in one.
Array(expr string) string
// Each is a relation with one row per element of expr, in a column
// named value. It is correlated with the row expr came from, so it
// belongs in a FROM or JOIN alongside that row's table.
Each(expr string) string
// Length counts the elements of expr. An empty or null column is 0.
Length(expr string) string
// Extract reads path out of expr as text, null when path is absent.
// path is a JSON path relative to the value, ".a.b" or "[0]" or ""
// for the value itself.
Extract(expr, path string) string
// Last reads the final element of expr as text, "" when there is none.
Last(expr string) string
// Catalog is a relation over the schema's own objects, with columns
// type ("table", "view" or "index"), name, tbl_name and sql.
Catalog() string
// Columns is a relation over the schema's columns, with tbl_name, cid,
// name, type, notnull, dflt_value and pk.
Columns() string
// Prelude is the statements a schema needs before any of it exists —
// collations and the like — "" where the engine already has them.
Prelude() string
// Format is the name of the function rendering an instant through a
// format string, "" where the engine has none and a caller must refuse
// rather than approximate.
Format() string
// Row is the column carrying insertion order, "" where the engine has
// none and a caller must fall back to an ordinary column.
Row() string
// Optimize refreshes the planner's statistics.
Optimize() string
// Checkpoint folds the write-ahead log back into the database, "" where
// the engine has no log to fold.
Checkpoint() string
}
Dialect is one engine's spelling.
type Postgres ¶
type Postgres struct{}
Postgres spells for the PostgreSQL engine.
func (Postgres) Bool ¶ added in v0.6.25
Quoted, so that one spelling serves both operands a truth value is compared to: beside a boolean the literal reads as a boolean, and beside a value read out of a JSON document it reads as the text that document held.
func (Postgres) Checkpoint ¶
func (Postgres) Like ¶ added in v0.6.25
ILIKE rather than the nocase collation below, which LIKE accepts only from PostgreSQL 18 on.
type SQLite ¶
type SQLite struct{}
SQLite spells for the SQLite engine.
Source Files