diff --git a/spec/query_generator_spec.rb b/spec/query_generator_spec.rb
new file mode 100644
index 0000000..4226f20
--- /dev/null
+++ b/spec/query_generator_spec.rb
@@ -0,0 +1,95 @@
+require './text_to_sql_query'
+
+class SqlGeneratorTester
+  describe 'Testing query generator' do
+    it 'tests simple search term without column name and without quotes' do
+      @query = TextToSqlQuery.new('-123', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['players.device_id LIKE ?', '%-123%']
+    end
+
+    it 'tests simple search term with column name and without quotes' do
+      @query = TextToSqlQuery.new('title:ab', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['players.title LIKE ?', '%ab%']
+    end
+
+    it 'tests simple search term with unknown column name and without quotes' do
+      @query = TextToSqlQuery.new('unknown:ab', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['players.device_id LIKE ?', '%ab%']
+    end
+
+    it 'tests simple search term without column name and with quotes' do
+      @query = TextToSqlQuery.new('"ab"', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['players.device_id LIKE ?', '%"ab"%']
+    end
+
+    it 'tests simple search term with column name and with quotes' do
+      @query = TextToSqlQuery.new('tag:"ab"', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['players.tag LIKE ?', '%"ab"%']
+    end
+
+    it 'tests search without operators' do
+      @query = TextToSqlQuery.new('123 456', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['(players.device_id LIKE ? OR players.device_id LIKE ?)', '%123%', '%456%']
+    end
+
+    it 'tests search with OR operator' do
+      @query = TextToSqlQuery.new('123 or 456', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['(players.device_id LIKE ? OR players.device_id LIKE ?)', '%123%', '%456%']
+    end
+
+    it 'tests search with AND operator' do
+      @query = TextToSqlQuery.new('123 and 456', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['(players.device_id LIKE ? AND players.device_id LIKE ?)', '%123%', '%456%']
+    end
+
+    it 'tests search with NOT operator on default column' do
+      @query = TextToSqlQuery.new('not 23', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['NOT players.device_id LIKE ?', '%23%']
+    end
+
+    it 'tests search with NOT operator on non-default column' do
+      @query = TextToSqlQuery.new('not tag:23', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['NOT players.tag LIKE ?', '%23%']
+    end
+
+    it 'tests search with mixed logical operators' do
+      @query = TextToSqlQuery.new('title:ab and not tag:hf-1', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['(players.title LIKE ? AND NOT players.tag LIKE ?)', '%ab%', '%hf-1%']
+    end
+
+    it 'tests search with mixed logical operators without NOT' do
+      @query = TextToSqlQuery.new('title:a and title:b or title:c', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['((players.title LIKE ? AND players.title LIKE ?) OR players.title LIKE ?)', '%a%', '%b%', '%c%']
+    end
+
+    it 'tests search with brackets in expression' do
+      @query = TextToSqlQuery.new('title:a and (title:b or title:c)', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['(players.title LIKE ? AND (players.title LIKE ? OR players.title LIKE ?))', '%a%', '%b%', '%c%']
+    end
+
+    it 'tests search with brackets in expression and with NOT operator' do
+      @query = TextToSqlQuery.new('title:a and not (title:b or title:c)', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['(players.title LIKE ? AND NOT (players.title LIKE ? OR players.title LIKE ?))', '%a%', '%b%', '%c%']
+    end
+
+    it 'tests search with special characters in search term' do
+      @query = TextToSqlQuery.new('title:"%a_\"', [:'players.title', :'players.tag', :'players.device_id'], :'players.device_id')
+
+      expect(@query.where_clause).to eq ['players.title LIKE ?', '%"\%a\_\\"%']
+    end
+  end
+end
\ No newline at end of file
diff --git a/text_to_sql_query.rb b/text_to_sql_query.rb
new file mode 100644
index 0000000..241149a
--- /dev/null
+++ b/text_to_sql_query.rb
@@ -0,0 +1,90 @@
+require './parser'
+
+class TextToSqlQuery
+  def initialize(text, fields, default_field, fields_mappings = {})
+    @text = text.to_s.strip
+    @fields = fields.map(&:to_sym)
+    @default_field = default_field.to_sym
+    @fields_mappings = fields_mappings.merge(@fields.reduce({}) do |mappings, field|
+      _table_name, field_name = field.to_s.split('.')
+      mappings[field_name.to_sym] = field
+      mappings
+    end)
+  end
+
+  def where_clause
+    @parser = Query.new
+    @parsed_tree = @parser.parse(@text)
+    generate_sql @parsed_tree
+  end
+
+  private
+
+  def generate_sql(tree)
+    first_key = tree.keys.first
+    node_value = tree[first_key]
+    case first_key
+    when :DEFAULT_COLUMN
+      escaped_node_value = escape_special_chars node_value
+      ["#{@default_field.to_s} LIKE ?", "%#{escaped_node_value}%"]
+    when :OPERATOR_OR
+      generate_expression_for_logical_operator(:OR, node_value)
+    when :OPERATOR_AND
+      generate_expression_for_logical_operator(:AND, node_value)
+    when :OPERATOR_NOT
+      not_array = generate_sql node_value
+
+      if not_array.length < 2
+        raise "There should be more than 1 element for expression following NOT operator"
+      end
+
+      not_expression = not_array.first
+      not_params = not_array[1..]
+
+      ["NOT #{not_expression}"] + not_params
+
+    else
+      # key is column name
+      escaped_node_value = escape_special_chars node_value
+      mapping = @fields_mappings[first_key.to_sym]
+      if mapping.nil?
+        ["#{@default_field.to_s} LIKE ?", "%#{escaped_node_value}%"]
+      else
+        ["#{mapping.to_s} LIKE ?", "%#{escaped_node_value}%"]
+      end
+    end
+  end
+
+  def generate_expression_for_logical_operator(operator, operator_array)
+    if operator_array.length != 2
+      raise "There should be two array elements for #{operator.to_s} operator"
+    end
+
+    first_operand = generate_sql operator_array.first
+    second_operand = generate_sql operator_array.last
+
+    if first_operand.length < 2
+      raise 'There should be more than 1 element in first operand array'
+    end
+
+    if second_operand.length < 2
+      raise 'There should be more than 1 element in second operand array'
+    end
+
+    first_operand_expression = first_operand.first
+    first_operand_params = first_operand[1..]
+
+    second_operand_expression = second_operand.first
+    second_operand_params = second_operand[1..]
+
+    ["(#{first_operand_expression} #{operator.to_s} #{second_operand_expression})"] + first_operand_params + second_operand_params
+  end
+
+  def escape_special_chars(text)
+    result = text
+    result.gsub!(/\_/, '\_')
+    result.tr!('\\', '\\')
+    result.gsub!(/%/, '\%')
+    result
+  end
+end
\ No newline at end of file