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286
qry_select.go
Normal file
286
qry_select.go
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// Patial Tech.
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// Author, Ankit Patial
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package pgm
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import (
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"context"
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"errors"
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"fmt"
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"strconv"
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"strings"
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"github.com/jackc/pgx/v5"
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)
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type (
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selectQry struct {
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table string
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fields []Field
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args []any
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join []string
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where []Conditioner
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groupBy []Field
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having []Conditioner
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orderBy []Field
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limit int
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offset int
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debug bool
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}
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CondAction uint8
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Cond struct {
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Val any
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op string
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Field string
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len int
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action CondAction
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}
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CondGroup struct {
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op string
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cond []Conditioner
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}
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)
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// Contdition actions
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const (
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CondActionNothing CondAction = iota
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CondActionNeedToClose
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CondActionSubQuery
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)
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// Select clause
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func (t Table) Select(field ...Field) SelectClause {
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qb := &selectQry{
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table: t.Name,
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debug: t.debug,
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fields: field,
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}
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return qb
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}
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func (q *selectQry) Join(t Table, t1Field, t2Field Field) SelectClause {
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q.join = append(q.join, "JOIN "+t.Name+" ON "+t1Field.String()+" = "+t2Field.String())
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return q
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}
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func (q *selectQry) LeftJoin(t Table, t1Field, t2Field Field) SelectClause {
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q.join = append(q.join, "LEFT JOIN "+t.Name+" ON "+t1Field.String()+" = "+t2Field.String())
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return q
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}
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func (q *selectQry) RightJoin(t Table, t1Field, t2Field Field) SelectClause {
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q.join = append(q.join, "RIGHT JOIN "+t.Name+" ON "+t1Field.String()+" = "+t2Field.String())
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return q
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}
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func (q *selectQry) FullJoin(t Table, t1Field, t2Field Field) SelectClause {
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q.join = append(q.join, "FULL JOIN "+t.Name+" ON "+t1Field.String()+" = "+t2Field.String())
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return q
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}
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func (q *selectQry) CrossJoin(t Table) SelectClause {
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q.join = append(q.join, "CROSS JOIN "+t.Name)
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return q
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}
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func (q *selectQry) Where(cond ...Conditioner) AfterWhere {
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q.where = append(q.where, cond...)
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return q
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}
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func (q *selectQry) OrderBy(fields ...Field) AfterOrderBy {
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q.orderBy = fields
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return q
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}
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func (q *selectQry) GroupBy(fields ...Field) AfterGroupBy {
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q.groupBy = fields
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return q
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}
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func (q *selectQry) Having(cond ...Conditioner) AfterHaving {
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q.having = append(q.having, cond...)
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return q
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}
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func (q *selectQry) Limit(v int) AfterLimit {
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q.limit = v
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return q
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}
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func (q *selectQry) Offset(v int) AfterOffset {
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q.offset = v
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return q
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}
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func (q *selectQry) First(ctx context.Context, dest ...any) error {
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return poolPGX.Load().QueryRow(ctx, q.String(), q.args...).Scan(dest...)
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}
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func (q *selectQry) FirstTx(ctx context.Context, tx pgx.Tx, dest ...any) error {
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return tx.QueryRow(ctx, q.String(), q.args...).Scan(dest...)
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}
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func (q *selectQry) All(ctx context.Context, row RowsCb) error {
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rows, err := poolPGX.Load().Query(ctx, q.String(), q.args...)
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if errors.Is(err, pgx.ErrNoRows) {
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return ErrNoRows
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}
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defer rows.Close()
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for rows.Next() {
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if err := row(rows); err != nil {
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return err
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}
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}
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return nil
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}
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func (q *selectQry) AllTx(ctx context.Context, tx pgx.Tx, row RowsCb) error {
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rows, err := tx.Query(ctx, q.String(), q.args...)
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if errors.Is(err, pgx.ErrNoRows) {
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return ErrNoRows
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}
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defer rows.Close()
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for rows.Next() {
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if err := row(rows); err != nil {
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return err
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}
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}
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return nil
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}
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func (q *selectQry) raw(prefixArgs []any) (string, []any) {
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q.args = append(prefixArgs, q.args...)
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return q.String(), q.args
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}
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func (q *selectQry) String() string {
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sb := getSB()
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defer putSB(sb)
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sb.Grow(q.averageLen())
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// SELECT
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sb.WriteString("SELECT ")
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sb.WriteString(joinFileds(q.fields))
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sb.WriteString(" FROM " + q.table)
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// JOIN
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if len(q.join) > 0 {
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sb.WriteString(" " + strings.Join(q.join, " "))
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}
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// WHERE
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if len(q.where) > 0 {
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sb.WriteString(" WHERE ")
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var argIdx int
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for i, c := range q.where {
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argIdx = len(q.args)
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if i > 0 {
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sb.WriteString(" AND ")
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}
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sb.WriteString(c.Condition(&q.args, argIdx))
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}
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}
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// GROUP BY
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if len(q.groupBy) > 0 {
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sb.WriteString(" GROUP BY ")
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sb.WriteString(joinFileds(q.groupBy))
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}
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// HAVING
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if len(q.having) > 0 {
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sb.WriteString(" HAVING ")
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var argIdx int
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for i, c := range q.having {
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argIdx = len(q.args)
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if i > 0 {
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sb.WriteString(" AND ")
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}
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sb.WriteString(c.Condition(&q.args, argIdx))
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}
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}
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// ORDER BY
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if len(q.orderBy) > 0 {
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sb.WriteString(" ORDER BY ")
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sb.WriteString(joinFileds(q.orderBy))
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}
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// LIMIT
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if q.limit > 0 {
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sb.WriteString(" LIMIT ")
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sb.WriteString(strconv.Itoa(q.limit))
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}
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// OFFSET
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if q.offset > 0 {
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sb.WriteString(" OFFSET ")
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sb.WriteString(strconv.Itoa(q.offset))
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}
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qry := sb.String()
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if q.debug {
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fmt.Println("***")
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fmt.Println(qry)
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fmt.Printf("%+v\n", q.args)
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fmt.Println("***")
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}
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return qry
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}
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func (q *selectQry) averageLen() int {
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n := 12 + len(q.table) // SELECT FROM <tbl_name>
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for _, c := range q.fields {
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n += (len(c) + 2) * len(q.table) // columns with tablename.columnname
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}
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// JOIN
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if len(q.join) > 0 {
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for _, c := range q.join {
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n += len(c) + 2 // with whitespace
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}
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}
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// WHERE
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if len(q.where) > 0 {
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n += 7 + len(q.args)*5 // WHERE with 2 sapces and each args roughly with min of 5 char
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}
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// GROUP BY
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if len(q.groupBy) > 0 {
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n += 10 // GROUP BY
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for _, c := range q.groupBy {
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n += len(c) + 2 // one command and a whitespace
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}
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}
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// ORDER BY
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if len(q.orderBy) > 0 {
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n += 10 // ORDER BY
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for _, c := range q.orderBy {
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n += len(c) + 2 // one command and a whitespace
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}
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}
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// LIMIT
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if q.limit > 0 {
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n += 10 // LIMIT
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}
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// OFFSET
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if q.offset > 0 {
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n += 10 // OFFSET
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}
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return n
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}
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