Caché Upgrade Checklists - InterSystems Documentation

Developers5.2.8.4 Reserved Word Checking More ComprehensiveIn prior versions, a reserved word would be accepted as an identifier, for example:• As an alias following AS in a SELECT or FROM clause,• As a table reference in a FROM clauseThese occurrences will now be reported as errors. This is unlikely to affect many queries since the reserved word could notbe used in WHERE, GROUP BY, HAVING, or SELECT clauses, nor as the table qualifying name for a column.5.2.8.5 ORDER Is No Longer A Reserved WordORDER is no longer a reserved word. It is now a non-reserved keyword. ORDER can be used everywhere a regular identifieris used.5.2.8.6 Use Of TOP and ORDER In SubqueriesIn prior versions, there were two equivalent ways to apply TOP to a UNION:SELECT TOP ...FROM (SELECT .... UNION ... SELECT ...)ORDER BY ...andSELECT TOP ......UNION...SELECT...ORDER BYStarting with this version, the first syntax form will be required. The second example is considered a defect where TOPalways applied to the outermost processing level no matter where it was specified.5.2.8.7 CASE Clause Result Type ChangeIn prior versions, the type reported by a CASE expression would be the same as the first potential return value of the CASEexpression. This has been changed to return the best compatible type of all the possible return value types of the CASEexpression. Caché will now also use the largest length, precision, and scale of all the potential return values; this appliesto numeric return values only.The precedence of return types (highest to lowest) is:• DOUBLE• NUMERIC• BIGINT• INTEGER• SMALLINT• TINYINTThus, if a CASE expression may potentially return TINYINT, INTEGER, or NUMERIC values, the type of the columnwill be NUMERIC because NUMERIC has the highest precedence.Caché Upgrade Checklists 125