github.com/yongjacky/phoenix-go-orm-builder@v0.3.5/builder_select.go (about)

     1  // Copyright 2016 The Xorm Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package builder
     6  
     7  import (
     8  	"fmt"
     9  )
    10  
    11  // Select creates a select Builder
    12  func Select(cols ...string) *Builder {
    13  	builder := &Builder{cond: NewCond()}
    14  	return builder.Select(cols...)
    15  }
    16  
    17  func (b *Builder) selectWriteTo(w Writer) error {
    18  	if len(b.from) <= 0 && !b.isNested {
    19  		return ErrNoTableName
    20  	}
    21  
    22  	// perform limit before writing to writer when b.dialect between ORACLE and MSSQL
    23  	// this avoid a duplicate writing problem in simple limit query
    24  	if b.limitation != nil && (b.dialect == ORACLE || b.dialect == MSSQL) {
    25  		return b.limitWriteTo(w)
    26  	}
    27  
    28  	if _, err := fmt.Fprint(w, "SELECT "); err != nil {
    29  		return err
    30  	}
    31  	if len(b.selects) > 0 {
    32  		for i, s := range b.selects {
    33  			if _, err := fmt.Fprint(w, s); err != nil {
    34  				return err
    35  			}
    36  			if i != len(b.selects)-1 {
    37  				if _, err := fmt.Fprint(w, ","); err != nil {
    38  					return err
    39  				}
    40  			}
    41  		}
    42  	} else {
    43  		if _, err := fmt.Fprint(w, "*"); err != nil {
    44  			return err
    45  		}
    46  	}
    47  
    48  	if b.subQuery == nil {
    49  		if _, err := fmt.Fprint(w, " FROM ", b.from); err != nil {
    50  			return err
    51  		}
    52  	} else {
    53  		if b.cond.IsValid() && len(b.from) <= 0 {
    54  			return ErrUnnamedDerivedTable
    55  		}
    56  		if b.subQuery.dialect != "" && b.dialect != b.subQuery.dialect {
    57  			return ErrInconsistentDialect
    58  		}
    59  
    60  		// dialect of sub-query will inherit from the main one (if not set up)
    61  		if b.dialect != "" && b.subQuery.dialect == "" {
    62  			b.subQuery.dialect = b.dialect
    63  		}
    64  
    65  		switch b.subQuery.optype {
    66  		case selectType, setOpType:
    67  			fmt.Fprint(w, " FROM (")
    68  			if err := b.subQuery.WriteTo(w); err != nil {
    69  				return err
    70  			}
    71  
    72  			if len(b.from) == 0 {
    73  				fmt.Fprintf(w, ")")
    74  			} else {
    75  				fmt.Fprintf(w, ") %v", b.from)
    76  			}
    77  		default:
    78  			return ErrUnexpectedSubQuery
    79  		}
    80  	}
    81  
    82  	for _, v := range b.joins {
    83  		b, ok := v.joinTable.(*Builder)
    84  		if ok {
    85  			if _, err := fmt.Fprintf(w, " %s JOIN (", v.joinType); err != nil {
    86  				return err
    87  			}
    88  			if err := b.WriteTo(w); err != nil {
    89  				return err
    90  			}
    91  			if _, err := fmt.Fprintf(w, ") ON "); err != nil {
    92  				return err
    93  			}
    94  		} else {
    95  			if _, err := fmt.Fprintf(w, " %s JOIN %s ON ", v.joinType, v.joinTable); err != nil {
    96  				return err
    97  			}
    98  		}
    99  
   100  		if err := v.joinCond.WriteTo(w); err != nil {
   101  			return err
   102  		}
   103  	}
   104  
   105  	if b.cond.IsValid() {
   106  		if _, err := fmt.Fprint(w, " WHERE "); err != nil {
   107  			return err
   108  		}
   109  
   110  		if err := b.cond.WriteTo(w); err != nil {
   111  			return err
   112  		}
   113  	}
   114  
   115  	if len(b.groupBy) > 0 {
   116  		if _, err := fmt.Fprint(w, " GROUP BY ", b.groupBy); err != nil {
   117  			return err
   118  		}
   119  	}
   120  
   121  	if len(b.having) > 0 {
   122  		if _, err := fmt.Fprint(w, " HAVING ", b.having); err != nil {
   123  			return err
   124  		}
   125  	}
   126  
   127  	if len(b.orderBy) > 0 {
   128  		if _, err := fmt.Fprint(w, " ORDER BY ", b.orderBy); err != nil {
   129  			return err
   130  		}
   131  	}
   132  
   133  	if b.limitation != nil {
   134  		if err := b.limitWriteTo(w); err != nil {
   135  			return err
   136  		}
   137  	}
   138  
   139  	return nil
   140  }
   141  
   142  // OrderBy orderBy SQL
   143  func (b *Builder) OrderBy(orderBy string) *Builder {
   144  	b.orderBy = orderBy
   145  	return b
   146  }
   147  
   148  // GroupBy groupby SQL
   149  func (b *Builder) GroupBy(groupby string) *Builder {
   150  	b.groupBy = groupby
   151  	return b
   152  }
   153  
   154  // Having having SQL
   155  func (b *Builder) Having(having string) *Builder {
   156  	b.having = having
   157  	return b
   158  }