forked from doug-martin/goqu
/
select_sql_generator.go
252 lines (230 loc) · 7.89 KB
/
select_sql_generator.go
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package sqlgen
import (
"github.com/GlebBeloded/goqu/v9/exp"
"github.com/GlebBeloded/goqu/v9/internal/errors"
"github.com/GlebBeloded/goqu/v9/internal/sb"
)
type (
// An adapter interface to be used by a Dataset to generate SQL for a specific dialect.
// See DefaultAdapter for a concrete implementation and examples.
SelectSQLGenerator interface {
Dialect() string
Generate(b sb.SQLBuilder, clauses exp.SelectClauses)
}
// The default adapter. This class should be used when building a new adapter. When creating a new adapter you can
// either override methods, or more typically update default values.
// See (github.com/GlebBeloded/goqu/adapters/postgres)
selectSQLGenerator struct {
*commonSQLGenerator
}
)
func errNotSupportedJoinType(j exp.JoinExpression) error {
return errors.New("dialect does not support %v", j.JoinType())
}
func errJoinConditionRequired(j exp.JoinExpression) error {
return errors.New("join condition required for conditioned join %v", j.JoinType())
}
func errDistinctOnNotSupported(dialect string) error {
return errors.New("dialect does not support DISTINCT ON clause [dialect=%s]", dialect)
}
func errWindowNotSupported(dialect string) error {
return errors.New("dialect does not support WINDOW clause [dialect=%s]", dialect)
}
var errNoWindowName = errors.New("window expresion has no valid name")
func NewSelectSQLGenerator(dialect string, do *SQLDialectOptions) SelectSQLGenerator {
return &selectSQLGenerator{newCommonSQLGenerator(dialect, do)}
}
func (ssg *selectSQLGenerator) Dialect() string {
return ssg.dialect
}
func (ssg *selectSQLGenerator) Generate(b sb.SQLBuilder, clauses exp.SelectClauses) {
for _, f := range ssg.dialectOptions.SelectSQLOrder {
if b.Error() != nil {
return
}
switch f {
case CommonTableSQLFragment:
ssg.esg.Generate(b, clauses.CommonTables())
case SelectSQLFragment:
ssg.SelectSQL(b, clauses)
case SelectWithLimitSQLFragment:
ssg.SelectWithLimitSQL(b, clauses)
case FromSQLFragment:
ssg.FromSQL(b, clauses.From())
case JoinSQLFragment:
ssg.JoinSQL(b, clauses.Joins())
case WhereSQLFragment:
ssg.WhereSQL(b, clauses.Where())
case GroupBySQLFragment:
ssg.GroupBySQL(b, clauses.GroupBy())
case HavingSQLFragment:
ssg.HavingSQL(b, clauses.Having())
case WindowSQLFragment:
ssg.WindowSQL(b, clauses.Windows())
case CompoundsSQLFragment:
ssg.CompoundsSQL(b, clauses.Compounds())
case OrderSQLFragment:
ssg.OrderSQL(b, clauses.Order())
case OrderWithOffsetFetchSQLFragment:
ssg.OrderWithOffsetFetchSQL(b, clauses.Order(), clauses.Offset(), clauses.Limit())
case LimitSQLFragment:
ssg.LimitSQL(b, clauses.Limit())
case OffsetSQLFragment:
ssg.OffsetSQL(b, clauses.Offset())
case ForSQLFragment:
ssg.ForSQL(b, clauses.Lock())
default:
b.SetError(errNotSupportedFragment("SELECT", f))
}
}
}
func (ssg *selectSQLGenerator) selectSQLCommon(b sb.SQLBuilder, clauses exp.SelectClauses) {
dc := clauses.Distinct()
if dc != nil {
b.Write(ssg.dialectOptions.DistinctFragment)
if !dc.IsEmpty() {
if ssg.dialectOptions.SupportsDistinctOn {
b.Write(ssg.dialectOptions.OnFragment).WriteRunes(ssg.dialectOptions.LeftParenRune)
ssg.esg.Generate(b, dc)
b.WriteRunes(ssg.dialectOptions.RightParenRune, ssg.dialectOptions.SpaceRune)
} else {
b.SetError(errDistinctOnNotSupported(ssg.dialect))
return
}
} else {
b.WriteRunes(ssg.dialectOptions.SpaceRune)
}
}
cols := clauses.Select()
if clauses.IsDefaultSelect() || len(cols.Columns()) == 0 {
b.WriteRunes(ssg.dialectOptions.StarRune)
} else {
ssg.esg.Generate(b, cols)
}
}
// Adds the SELECT clause and columns to a sql statement
func (ssg *selectSQLGenerator) SelectSQL(b sb.SQLBuilder, clauses exp.SelectClauses) {
b.Write(ssg.dialectOptions.SelectClause).WriteRunes(ssg.dialectOptions.SpaceRune)
ssg.selectSQLCommon(b, clauses)
}
// Adds the SELECT clause along with LIMIT to a SQL statement (e.g. MSSQL dialect: SELECT TOP 10 ...)
func (ssg *selectSQLGenerator) SelectWithLimitSQL(b sb.SQLBuilder, clauses exp.SelectClauses) {
b.Write(ssg.dialectOptions.SelectClause).WriteRunes(ssg.dialectOptions.SpaceRune)
if clauses.Offset() == 0 && clauses.Limit() != nil {
ssg.LimitSQL(b, clauses.Limit())
b.WriteRunes(ssg.dialectOptions.SpaceRune)
}
ssg.selectSQLCommon(b, clauses)
}
// Generates the JOIN clauses for an SQL statement
func (ssg *selectSQLGenerator) JoinSQL(b sb.SQLBuilder, joins exp.JoinExpressions) {
if len(joins) > 0 {
for _, j := range joins {
joinType, ok := ssg.dialectOptions.JoinTypeLookup[j.JoinType()]
if !ok {
b.SetError(errNotSupportedJoinType(j))
return
}
b.Write(joinType)
ssg.esg.Generate(b, j.Table())
if t, ok := j.(exp.ConditionedJoinExpression); ok {
if t.IsConditionEmpty() {
b.SetError(errJoinConditionRequired(j))
return
}
ssg.joinConditionSQL(b, t.Condition())
}
}
}
}
// Generates the GROUP BY clause for an SQL statement
func (ssg *selectSQLGenerator) GroupBySQL(b sb.SQLBuilder, groupBy exp.ColumnListExpression) {
if groupBy != nil && len(groupBy.Columns()) > 0 {
b.Write(ssg.dialectOptions.GroupByFragment)
ssg.esg.Generate(b, groupBy)
}
}
// Generates the HAVING clause for an SQL statement
func (ssg *selectSQLGenerator) HavingSQL(b sb.SQLBuilder, having exp.ExpressionList) {
if having != nil && len(having.Expressions()) > 0 {
b.Write(ssg.dialectOptions.HavingFragment)
ssg.esg.Generate(b, having)
}
}
// Generates the OFFSET clause for an SQL statement
func (ssg *selectSQLGenerator) OffsetSQL(b sb.SQLBuilder, offset uint) {
if offset > 0 {
b.Write(ssg.dialectOptions.OffsetFragment)
ssg.esg.Generate(b, offset)
}
}
// Generates the compound sql clause for an SQL statement (e.g. UNION, INTERSECT)
func (ssg *selectSQLGenerator) CompoundsSQL(b sb.SQLBuilder, compounds []exp.CompoundExpression) {
for _, compound := range compounds {
ssg.esg.Generate(b, compound)
}
}
// Generates the FOR (aka "locking") clause for an SQL statement
func (ssg *selectSQLGenerator) ForSQL(b sb.SQLBuilder, lockingClause exp.Lock) {
if lockingClause == nil {
return
}
switch lockingClause.Strength() {
case exp.ForNolock:
return
case exp.ForUpdate:
b.Write(ssg.dialectOptions.ForUpdateFragment)
case exp.ForNoKeyUpdate:
b.Write(ssg.dialectOptions.ForNoKeyUpdateFragment)
case exp.ForShare:
b.Write(ssg.dialectOptions.ForShareFragment)
case exp.ForKeyShare:
b.Write(ssg.dialectOptions.ForKeyShareFragment)
}
// the WAIT case is the default in Postgres, and is what you get if you don't specify NOWAIT or
// SKIP LOCKED. There's no special syntax for it in PG, so we don't do anything for it here
switch lockingClause.WaitOption() {
case exp.NoWait:
b.Write(ssg.dialectOptions.NowaitFragment)
case exp.SkipLocked:
b.Write(ssg.dialectOptions.SkipLockedFragment)
}
}
func (ssg *selectSQLGenerator) WindowSQL(b sb.SQLBuilder, windows []exp.WindowExpression) {
weLen := len(windows)
if weLen == 0 {
return
}
if !ssg.dialectOptions.SupportsWindowFunction {
b.SetError(errWindowNotSupported(ssg.dialect))
return
}
b.Write(ssg.dialectOptions.WindowFragment)
for i, we := range windows {
if !we.HasName() {
b.SetError(errNoWindowName)
}
ssg.esg.Generate(b, we)
if i < weLen-1 {
b.WriteRunes(ssg.dialectOptions.CommaRune, ssg.dialectOptions.SpaceRune)
}
}
}
func (ssg *selectSQLGenerator) joinConditionSQL(b sb.SQLBuilder, jc exp.JoinCondition) {
switch t := jc.(type) {
case exp.JoinOnCondition:
ssg.joinOnConditionSQL(b, t)
case exp.JoinUsingCondition:
ssg.joinUsingConditionSQL(b, t)
}
}
func (ssg *selectSQLGenerator) joinUsingConditionSQL(b sb.SQLBuilder, jc exp.JoinUsingCondition) {
b.Write(ssg.dialectOptions.UsingFragment).
WriteRunes(ssg.dialectOptions.LeftParenRune)
ssg.esg.Generate(b, jc.Using())
b.WriteRunes(ssg.dialectOptions.RightParenRune)
}
func (ssg *selectSQLGenerator) joinOnConditionSQL(b sb.SQLBuilder, jc exp.JoinOnCondition) {
b.Write(ssg.dialectOptions.OnFragment)
ssg.esg.Generate(b, jc.On())
}