| Class | Sequel::SQL::BooleanExpression |
| In: |
lib/sequel/sql.rb
|
| Parent: | ComplexExpression |
Subclass of ComplexExpression where the expression results in a boolean value in SQL.
Take pairs of values (e.g. a hash or array of two element arrays) and converts it to a BooleanExpression. The operator and args used depends on the case of the right (2nd) argument:
| 0..10 : | left >= 0 AND left <= 10 |
| nil : | left IS NULL |
| true : | left IS TRUE |
| false : | left IS FALSE |
| /as/ : | left ~ ‘as‘ |
| :blah : | left = blah |
| ‘blah’ : | left = ‘blah‘ |
If multiple arguments are given, they are joined with the op given (AND by default, OR possible). If negate is set to true, all subexpressions are inverted before used. Therefore, the following expressions are equivalent:
~from_value_pairs(hash) from_value_pairs(hash, :OR, true)
# File lib/sequel/sql.rb, line 1054
1054: def self.from_value_pairs(pairs, op=:AND, negate=false)
1055: pairs = pairs.map{|l,r| from_value_pair(l, r)}
1056: pairs.map!{|ce| invert(ce)} if negate
1057: pairs.length == 1 ? pairs[0] : new(op, *pairs)
1058: end
Invert the expression, if possible. If the expression cannot be inverted, raise an error. An inverted expression should match everything that the uninverted expression did not match, and vice-versa, except for possible issues with SQL NULL (i.e. 1 == NULL is NULL and 1 != NULL is also NULL).
BooleanExpression.invert(:a) # NOT "a"
# File lib/sequel/sql.rb, line 1091
1091: def self.invert(ce)
1092: case ce
1093: when BooleanExpression
1094: case op = ce.op
1095: when :AND, :OR
1096: BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)})
1097: else
1098: BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1099: end
1100: when StringExpression, NumericExpression
1101: raise(Sequel::Error, "cannot invert #{ce.inspect}")
1102: when Constant
1103: CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
1104: else
1105: BooleanExpression.new(:NOT, ce)
1106: end
1107: end
Always use an AND operator for & on BooleanExpressions
# File lib/sequel/sql.rb, line 1110
1110: def &(ce)
1111: BooleanExpression.new(:AND, self, ce)
1112: end