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69 lines
2.1 KiB
Go
69 lines
2.1 KiB
Go
// Package dialect contains functionality for SQL dialects.
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package dialect
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import (
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"github.com/neilotoole/sq/libsq/core/jointype"
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"github.com/neilotoole/sq/libsq/source/drivertype"
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)
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// Dialect holds driver-specific SQL dialect values and functions.
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type Dialect struct {
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// Placeholders returns a string a SQL placeholders string.
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// For example "(?, ?, ?)" or "($1, $2, $3), ($4, $5, $6)".
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Placeholders func(numCols, numRows int) string
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// Enquote is a function that quotes and escapes an
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// identifier (such as a table or column name). Typically the func
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// uses the double-quote rune (although MySQL uses backtick).
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Enquote func(string) string
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// Ops is a map of overridden SLQ operator (e.g. "==" or "!=") to
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// its SQL rendering.
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Ops map[string]string
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// Type is the dialect's driver type.
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Type drivertype.Type `json:"type"`
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// Joins is the set of JOIN types (e.g. "RIGHT JOIN") that
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// the dialect supports. Not all drivers support each join type. For
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// example, MySQL doesn't support jointype.FullOuter.
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Joins []jointype.Type
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// MaxBatchValues is the maximum number of values in a batch insert.
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MaxBatchValues int
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// IntBool is true if BOOLEAN is handled as an INT by the DB driver.
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IntBool bool `json:"int_bool"`
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// Catalog indicates that the database supports the catalog concept,
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// in addition to schema. For example, PostgreSQL supports catalog
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// and schema (sakila.public.actor), whereas MySQL only supports schema
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// (sakila.actor).
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Catalog bool
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}
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// String returns a log/debug-friendly representation.
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func (d Dialect) String() string {
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return d.Type.String()
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}
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// defaultOps is a map of SLQ operator (e.g. "==" or "!=") to
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// its default SQL rendering.
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var defaultOps = map[string]string{
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`==`: `=`,
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`&&`: `AND`,
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`||`: `OR`,
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`!=`: `!=`,
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}
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// DefaultOps returns a default map of SLQ operator (e.g. "==" or "!=") to
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// its SQL rendering. The returned map is a copy and can be safely
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// modified by the caller.
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func DefaultOps() map[string]string {
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ops := make(map[string]string, len(defaultOps))
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for k, v := range defaultOps {
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ops[k] = v
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}
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return ops
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}
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