Once you get a hang of the very peculiar syntax, SQL is a highly expressive and rich language offering incredible features at a declarative level. One of the coolest features are window functions, whose coolness is in no proportion to their incredibly low popularity. The low popularity can only be due to developers being oblivious … Continue reading Probably the Coolest SQL Feature: Window Functions
Tag: sql standard
The Premature Return to SQL
In online communities, the NoSQL topic (much like the ORM topic) is a guarantee to stir emotions. Many emotions are stirred by evangelists on either side for ideological or marketing reasons. Here's an interesting post by Alex Popescu, a passionate NoSQL and polyglot persistence evangelist, claiming that the recent trend to return to SQL is … Continue reading The Premature Return to SQL
Oracle 12c Goodies: { CROSS | OUTER } APPLY
I can't believe my eyes. Has this been openly communicated by Oracle? I haven't seen too many blog posts on that matter. Apart from introducing the awesome SQL Standard OFFSET .. FETCH clause (just like SQL Server 2012), there seems to be now also { CROSS | OUTER } APPLY in Oracle 12c! Check out the … Continue reading Oracle 12c Goodies: { CROSS | OUTER } APPLY
jOOQ as a “PL/Java” language
Some people who get in touch with PL/SQL, PL/pgSQL, T-SQL, or any other proprietary procedural language for SQL interaction are probably missing out on a couple of language integration features in the Java world. Most Java APIs see SQL as an external domain-specific language that is "best" dealt with using string concatenation. Such APIs include: … Continue reading jOOQ as a “PL/Java” language
Emulating the SQL standard derived column list
Derived column lists are a fine feature, if your database supports them. The SQL:2008 standard specifies 7.6 <table reference> <table reference> ::= <table factor> | <joined table> <table factor> ::= <table primary> [ <sample clause> ] <table primary> ::= <table or query name> [ [ AS ] <correlation name> [ <left paren> <derived column list> … Continue reading Emulating the SQL standard derived column list
Row value expressions and the BETWEEN predicate
Now this is a simple example of how SQL clause simulation can get nasty if you want to make use of some more advanced SQL clauses that aren't supported in all databases. Consider the following predicate and equivalent transformations thereof: The BETWEEN predicate The BETWEEN predicate is a convenient form of expressing the fact that … Continue reading Row value expressions and the BETWEEN predicate
Row value expressions and the NULL predicate
Row value expressions are something very powerful in SQL. They have been around since the early days of standard SQL, e.g. in SQL 1992, even if not all databases implement them correctly, still today. As always, the NULL predicate is one that is a bit tricky to understand, also in the context of row value … Continue reading Row value expressions and the NULL predicate
The IS DISTINCT FROM predicate
The SQL-1999 standard specifies a useful IS DISTINCT FROM predicate, that behaves slightly different from the regular not equal comparison predicate. Here is its simple definition: 8.13 <distinct predicate> Format <distinct predicate> ::= <row value expression 3> IS DISTINCT FROM <row value expression 4> <row value expression 3> ::= <row value expression> <row value expression … Continue reading The IS DISTINCT FROM predicate