Add support for UNION statements
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zer0sub
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8 changed files with 140 additions and 219 deletions
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@ -1,196 +1,123 @@
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package sqlbuilder
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// By default, rows selected by a UNION statement are out-of-orderBy
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// If you have an ORDER BY on an inner SELECT statement, the only thing
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// it affects is the LIMIT clause on that inner statement (the ordering will
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// still be out-of-orderBy).
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import (
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"database/sql"
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"github.com/dropbox/godropbox/errors"
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"github.com/sub0zero/go-sqlbuilder/types"
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)
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type UnionStatement interface {
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Statement
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// Warning! You cannot include tableName names for the next 4 clauses, or
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// you'll get errors like:
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// Table 'server_file_journal' from one of the SELECTs cannot be used in
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// global ORDER clause
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Where(expression BoolExpression) UnionStatement
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GroupBy(expressions ...Expression) UnionStatement
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OrderBy(clauses ...OrderByClause) UnionStatement
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Limit(limit int64) UnionStatement
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Offset(offset int64) UnionStatement
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ORDER_BY(clauses ...OrderByClause) UnionStatement
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LIMIT(limit int64) UnionStatement
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OFFSET(offset int64) UnionStatement
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}
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//
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//func Union(selects ...SelectStatement) UnionStatement {
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// return &unionStatementImpl{
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// selects: selects,
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// limit: -1,
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// offset: -1,
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// unique: true,
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// }
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//}
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//
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//func UnionAll(selects ...SelectStatement) UnionStatement {
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// return &unionStatementImpl{
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// selects: selects,
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// limit: -1,
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// offset: -1,
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// unique: false,
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// }
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//}
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//
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//// Similar to selectStatementImpl, but less complete
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//type unionStatementImpl struct {
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// selects []SelectStatement
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// where BoolExpression
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// group *listClause
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// order *listClause
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// limit, offset int64
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// // True if results of the union should be deduped.
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// unique bool
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//}
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//
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//func (s *unionStatementImpl) Query(db types.Db, destination interface{}) error {
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// return Query(s, db, destination)
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//}
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//
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//func (u *unionStatementImpl) Execute(db types.Db) (res sql.Result, err error) {
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// return Execute(u, db)
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//}
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//
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//func (us *unionStatementImpl) Where(expression BoolExpression) UnionStatement {
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// us.where = expression
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// return us
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//}
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//
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//// Further filter the query, instead of replacing the filter
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//func (us *unionStatementImpl) AndWhere(expression BoolExpression) UnionStatement {
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// if us.where == nil {
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// return us.Where(expression)
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// }
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// us.where = And(us.where, expression)
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// return us
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//}
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//
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//func (us *unionStatementImpl) GroupBy(
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// expressions ...Expression) UnionStatement {
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//
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// us.group = &listClause{
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// clauses: make([]Clause, len(expressions), len(expressions)),
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// includeParentheses: false,
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// }
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//
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// for i, e := range expressions {
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// us.group.clauses[i] = e
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// }
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// return us
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//}
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//
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//func (us *unionStatementImpl) OrderBy(
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// clauses ...OrderByClause) UnionStatement {
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//
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// us.order = newOrderByListClause(clauses...)
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// return us
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//}
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//
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//func (us *unionStatementImpl) Limit(limit int64) UnionStatement {
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// us.limit = limit
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// return us
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//}
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//
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//func (us *unionStatementImpl) Offset(offset int64) UnionStatement {
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// us.offset = offset
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// return us
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//}
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//
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//func (us *unionStatementImpl) String() (sql string, err error) {
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// if len(us.selects) == 0 {
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// return "", errors.Newf("Union statement must have at least one SELECT")
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// }
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//
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// if len(us.selects) == 1 {
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// return us.selects[0].String()
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// }
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//
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// // Union statements in MySQL require that the same number of columns in each subquery
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// var projections []Projection
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//
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// for _, statement := range us.selects {
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// // do a type assertion to get at the underlying struct
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// statementImpl, ok := statement.(*selectStatementImpl)
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// if !ok {
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// return "", errors.Newf(
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// "Expected inner select statement to be of type " +
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// "selectStatementImpl")
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// }
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//
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// // check that for limit for statements with orderBy by clauses
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// if statementImpl.orderBy != nil && statementImpl.limit < 0 {
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// return "", errors.Newf(
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// "All inner selects in Union statement must have LIMIT if " +
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// "they have ORDER BY")
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// }
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//
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// // check number of projections
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// if projections == nil {
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// projections = statementImpl.projections
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// } else {
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// if len(projections) != len(statementImpl.projections) {
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// return "", errors.Newf(
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// "All inner selects in Union statement must select the " +
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// "same number of columns. For sanity, you probably " +
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// "want to select the same tableName columns in the same " +
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// "orderBy. If you are selecting on multiple tables, " +
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// "use Null to pad to the right number of fields.")
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// }
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// }
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// }
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//
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// buf := new(bytes.Buffer)
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// for i, statement := range us.selects {
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// if i != 0 {
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// if us.unique {
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// _, _ = buf.WriteString(" UNION ")
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// } else {
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// _, _ = buf.WriteString(" UNION ALL ")
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// }
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// }
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// _, _ = buf.WriteString("(")
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// selectSql, err := statement.String()
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// if err != nil {
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// return "", err
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// }
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// _, _ = buf.WriteString(selectSql)
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// _, _ = buf.WriteString(")")
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// }
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//
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// if us.where != nil {
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// _, _ = buf.WriteString(" WHERE ")
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// if err = us.where.Serialize(buf); err != nil {
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// return
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// }
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// }
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//
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// if us.group != nil {
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// _, _ = buf.WriteString(" GROUP BY ")
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// if err = us.group.Serialize(buf); err != nil {
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// return
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// }
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// }
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//
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// if us.order != nil {
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// _, _ = buf.WriteString(" ORDER BY ")
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// if err = us.order.Serialize(buf); err != nil {
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// return
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// }
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// }
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//
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// if us.limit >= 0 {
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// if us.offset >= 0 {
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// _, _ = buf.WriteString(
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// fmt.Sprintf(" LIMIT %d, %d", us.offset, us.limit))
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// } else {
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// _, _ = buf.WriteString(fmt.Sprintf(" LIMIT %d", us.limit))
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// }
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// }
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// return buf.String(), nil
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//}
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func Union(selects ...SelectStatement) UnionStatement {
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return &unionStatementImpl{
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selects: selects,
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limit: -1,
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offset: -1,
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all: true,
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}
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}
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func UnionAll(selects ...SelectStatement) UnionStatement {
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return &unionStatementImpl{
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selects: selects,
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limit: -1,
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offset: -1,
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all: false,
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}
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}
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// Similar to selectStatementImpl, but less complete
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type unionStatementImpl struct {
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selects []SelectStatement
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order *listClause
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limit, offset int64
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// True if results of the union should be deduped.
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all bool
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}
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func (us *unionStatementImpl) Serialize(out *queryData, options ...serializeOption) error {
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if len(us.selects) == 0 {
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return errors.Newf("Union statement must have at least one SELECT")
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}
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out.WriteString("(")
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for i, selectStmt := range us.selects {
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if i > 0 {
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out.WriteString(" UNION ")
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if us.all {
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out.WriteString(" ALL ")
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}
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}
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err := selectStmt.Serialize(out, options...)
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if err != nil {
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return err
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}
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}
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out.WriteString(")")
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if us.order != nil {
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out.WriteString(" ORDER BY ")
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if err := us.order.Serialize(out, NO_TABLE_NAME); err != nil {
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return err
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}
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}
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if us.limit >= 0 {
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out.WriteString(" LIMIT ")
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out.InsertArgument(us.limit)
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}
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if us.offset >= 0 {
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out.WriteString(" OFFSET ")
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out.InsertArgument(us.offset)
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}
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return nil
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}
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func (us *unionStatementImpl) ORDER_BY(clauses ...OrderByClause) UnionStatement {
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us.order = newOrderByListClause(clauses...)
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return us
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}
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func (us *unionStatementImpl) LIMIT(limit int64) UnionStatement {
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us.limit = limit
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return us
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}
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func (us *unionStatementImpl) OFFSET(offset int64) UnionStatement {
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us.offset = offset
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return us
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}
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func (us *unionStatementImpl) Sql() (query string, args []interface{}, err error) {
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queryData := &queryData{}
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err = us.Serialize(queryData)
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if err != nil {
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return
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}
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return queryData.buff.String(), queryData.args, nil
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}
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func (s *unionStatementImpl) Query(db types.Db, destination interface{}) error {
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return Query(s, db, destination)
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}
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func (u *unionStatementImpl) Execute(db types.Db) (res sql.Result, err error) {
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return Execute(u, db)
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}
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