[FB4] A proposal for fixing #7880

[dmitry-lipetsk]

These changes force a server to return correct datatype for CAST(something as array datatype) - array type instead type of element.

1. Test of CAST(arrayColumn as ARRAY)

SQL> set sqlda_display on;
SQL> SELECT CAST(COL_I4 AS VARCHAR(128)[0:2]) FROM TEST_ARR1;

INPUT message field count: 0

OUTPUT message field count: 1
01: sqltype: 540 ARRAY Nullable scale: 0 subtype: 0 len: 8
  :  name: CAST  alias: CAST
  : table:   owner:

             CAST
=================
            111:0

Usage of UDFs with SCALAR_ARRAY-argument. These functions return different information about array: DIM, element DTYPE, element LENGTH

SQL> -- Bad column type: VARCHAR instead ARRAY
SQL> -- FETCH returns incorrect data
SQL> SELECT IBP_UDF__GET_ARR_DIM(CAST(COL_I4 AS VARCHAR(128)[0:2])) FROM TEST_ARR1;

IBP_UDF__GET_ARR_DIM
====================
                   1

SQL> SELECT IBP_UDF__GET_ARR_DESC_DTYPE(CAST(COL_I4 AS VARCHAR(128)[0:2])) FROM TEST_ARR1;

IBP_UDF__GET_ARR_DESC_DTYPE
===========================
                          9                                                                                                                                                                                                                                                                                                                                                                             

SQL> SELECT IBP_UDF__GET_ARR_DESC_LENGTH(CAST(COL_I4 AS VARCHAR(128)[0:2])) FROM TEST_ARR1;                                                                                                                                                                                                                                                                                                             IBP_UDF__GET_ARR_DESC_LENGTH
============================
                           4                                                                                                                                                                                                                                                                                                                                                                            

SQL> SELECT IBP_UDF__ADTYPE__VCH64(CAST(COL_I4 AS VARCHAR(128)[0:2])) FROM TEST_ARR1;                                                                                                                                                                                                                                                                                                                   IBP_UDF__ADTYPE__VCH64
======================
                     3                                                                                                                                                                                                                                                                                                                                                                                  

SQL> SELECT IBP_UDF__ADTYPE__CH64(CAST(COL_I4 AS VARCHAR(128)[0:2])) FROM TEST_ARR1;

IBP_UDF__ADTYPE__CH64
=====================
                    1

SQL> -- Bad column type: INTEGER instead ARRAY
SQL> -- FETCH returns conversion error from string "#x01#x01#x01#x00#x04# ....."
SQL> SELECT IBP_UDF__GET_ARR_DIM(CAST(COL_I4 AS INTEGER[0:2])) FROM TEST_ARR1;

IBP_UDF__GET_ARR_DIM
====================
                   1

SQL> SELECT IBP_UDF__GET_ARR_DESC_DTYPE(CAST(COL_I4 AS INTEGER[0:2])) FROM TEST_ARR1;

IBP_UDF__GET_ARR_DESC_DTYPE
===========================
                          9

SQL> SELECT IBP_UDF__ADTYPE__VCH64(CAST(COL_I4 AS INTEGER[0:2])) FROM TEST_ARR1;

IBP_UDF__ADTYPE__VCH64
======================
                     3

SQL> SELECT IBP_UDF__ADTYPE__CH64(CAST(COL_I4 AS INTEGER[0:2])) FROM TEST_ARR1;

IBP_UDF__ADTYPE__CH64
=====================
                    1

2. TEST OF CAST(? AS array datatype)

SQL> set sqlda_display on;
SQL> SELECT CAST(? AS INTEGER[0:2]) FROM RDB$DATABASE;

INPUT message field count: 1
01: sqltype: 540 ARRAY Nullable scale: 0 subtype: 0 len: 8
  :  name:   alias:
  : table:   owner:

OUTPUT message field count: 1
01: sqltype: 540 ARRAY Nullable scale: 0 subtype: 0 len: 8
  :  name: CAST  alias: CAST
  : table:   owner:

             CAST
=================
Statement failed, SQLSTATE = 07002
Dynamic SQL Error
-SQLDA error
-No SQLDA for input values provided