Anchored data types for variables

Previously we added anchored data type declarations for table columns, tables, cursors:

DECLARE a TYPE OF t1.a;   -- table column

DECLARE b ROW TYPE OF t1; -- table row

DECLARE c ROW TYPE OF c1; -- cursor row

Under terms of this tasks we'll add anchor references to other variables:

DECLARE var1 INT;

DECLARE var2 TYPE OF var1;

The following features will be supported:

• Nested anchor declarations (anchors to anchors)
• Anchors to implicit ROW variables
• Anchors to table and cursor ROW variables
• Only local SP variables will be supported (SP parameters and SP return values are out of scope of this task)
• Both TYPE OF (for sql_mode=default) and %TYPE (for sql_mode=ORACLE) will be supported

Example: Scalar declarations

DECLARE var1 INT;

DECLARE var2 TYPE OF var1;

DECLARE var3 TYPE OF var2;

Example: Scalar declarations for sql_mode=ORACLE

DECLARE

  var1 INT;

  var2 var1%TYPE;

  var3 var2%TYPE;

Example: Implicit ROW variables

DECLARE row1 ROW (a INT, b TEXT);

DECLARE row2 TYPE OF row1;

Example: Implicit ROW variables for sql_mode=ORACLE

DECLARE

  row1 ROW (a INT, b TEXT);

  row2 row1%TYPE;

Example: Table ROW variables

DECLARE row1 ROW TYPE OF table1;

DECLARE row2 TYPE OF row1;

Example: Table ROW variables for sql_mode=ORACLE

DECLARE

  row1 ROW TYPE OF table1;

  row2 row1%TYPE;

Example: Cursor ROW variables

DECLARE CURSOR cur1 AS SELECT 10 AS a, 'b' AS b;

DECLARE row1 ROW TYPE OF cur1;

DECLARE row2 TYPE OF row1;

Example: Cursor ROW variables for sql_mode=ORACLE

DECLARE

  CURSOR cur1 AS SELECT 10 AS a, 'b' AS b;

  row1 cur1%ROWTYPE;

  row2 row1%TYPE;