While jOOQ and Hibernate compete for the same target audience, they do not solve the same problem at all. You’ve already linked this article in your question. The essence of it is simple: Are you going to solve object graph persistence problems? Use an ORM (e.g. Hibernate) Are you going to embed SQL into Java? … Read more
It is excellent for staging mock tables when testing. For example, if your source tables contain millions of records and you want to test a small subset of data, you can use synonyms to re-direct the source table to a smaller table you control so you can stage various scenarios. In this way, you can … Read more
#tablename is a physical table, stored in tempdb that the server will drop automatically when the connection that created it is closed, @tablename is a table stored in memory & lives for the lifetime of the batch/procedure that created it, just like a local variable. You can only add a (non PK) index to a … Read more
You need a function to do the concatenation. Microsoft Access condense multiple lines in a table Example using your data: Select T.ColumnA , GetList(“Select ColumnB From Table1 As T1 Where T1.ColumnA = ” & [T].[ColumnA],””,”, “) AS ColumnBItems From Table1 AS T Group By T.ColumnA;
An index cannot safely be used in this case. A naive implementation would transform this: … WHERE word LIKE ‘search_string%’ into … WHERE word >= ‘search_string’ AND word < ‘search_strinh’ by incrementing the last character of the search string. The greater-than and less-than operators can use an index, where LIKE cannot. Unfortunately, that won’t work … Read more
Yes, index will help you, when using ORDER BY. Because INDEX is a sorted data structure, so the request will be executed faster. Look at this example: table test2 with 3 rows. I used LIMIT after order by to show the difference in execution. DROP TABLE IF EXISTS `test2`; CREATE TABLE `test2` ( `id` int(10) … Read more
I don’t know if this qualifies as “more elegant” but it is written in a different manner than Cybernate’s solution (although it is essentially the same) WITH window_table AS ( SELECT s.*, sum(volume) OVER previous_rows as total FROM stuff s WINDOW previous_rows as (ORDER BY priority desc ROWS between UNBOUNDED PRECEDING and CURRENT ROW) ) … Read more
According to the documentation, the difference is: REPLACE works exactly like INSERT, except that if an old row in the table has the same value as a new row for a PRIMARY KEY or a UNIQUE index, the old row is deleted before the new row is inserted. So what it does: Try to match … Read more
It indicates a “nationalized” a.k.a. unicode string constant. http://support.microsoft.com/kb/239530 When dealing with Unicode string constants in SQL Server you must precede all Unicode strings with a capital letter N, as documented in the SQL Server Books Online topic “Using Unicode Data”. http://msdn.microsoft.com/en-us/library/aa276823%28SQL.80%29.aspx nchar and nvarchar Character data types that are either fixed-length (nchar) or variable-length … Read more