Add ILIKE functionality

Author: alireza-ahmadi

lib/postgresql.js

@@ -389,9 +389,15 @@ PostgreSQL.prototype.buildExpression = function(columnName, operator,
     case 'like':
       return new ParameterizedSQL(columnName + " LIKE ? ESCAPE '\\'",
           [operatorValue]);
+    case 'ilike':
+      return new ParameterizedSQL(columnName + " ILIKE ? ESCAPE '\\'",
+          [operatorValue]);
     case 'nlike':
       return new ParameterizedSQL(columnName + " NOT LIKE ? ESCAPE '\\'",
           [operatorValue]);
+    case 'nilike':
+      return new ParameterizedSQL(columnName + " NOT ILIKE ? ESCAPE '\\'",
+          [operatorValue]);
     case 'regexp':
       if (operatorValue.global)
         g.warn('{{PostgreSQL}} regex syntax does not respect the {{`g`}} flag');