CreateQuery check_system_tables (children 3)
 Identifier check_system_tables
 Columns definition (children 1)
  ExpressionList (children 1)
   ColumnDeclaration key (children 1)
    DataType UInt16
 Storage definition (children 1)
  Function Buffer (children 1)
   ExpressionList (children 9)
    Function currentDatabase (children 1)
     ExpressionList
    Identifier check_system_tables_null
    Literal UInt64_2
    Literal UInt64_0
    Literal UInt64_100
    Literal UInt64_100
    Literal UInt64_100
    Literal UInt64_0
    Literal Float64_1000000
