Update: These articles in my blog describe the differences between the methods in more detail: NOT IN vs. NOT EXISTS vs. LEFT JOIN / IS NULL: SQL Server NOT IN vs. NOT EXISTS vs. LEFT JOIN / IS NULL: PostgreSQL NOT IN vs. NOT EXISTS vs. LEFT JOIN / IS NULL: Oracle NOT IN vs. NOT EXISTS vs. LEFT JOIN / IS NULL: MySQL There are three ways to do such a query: LEFT JOIN … Read more
An INNER JOIN can return data from the columns from both tables, and can duplicate values of records on either side have more than one match. A LEFT SEMI JOIN can only return columns from the left-hand table, and yields one of each record from the left-hand table where there is one or more matches in the right-hand table … Read more
That would have to be: Or, similar: You’re looking for something that contains “m” somewhere (SQL’s ‘%‘ operator is equivalent to regular expressions’ ‘.*‘), not something that has “m” anchored to the beginning of the string. Note: MongoDB uses regular expressions which are more powerful than “LIKE” in SQL. With regular expressions you can create any … Read more
You can do something like this: See, for example: https://dev.mysql.com/doc/refman/5.0/en/union.html
What is a LATERAL join? The feature was introduced with PostgreSQL 9.3. The manual: Subqueries appearing in FROM can be preceded by the key word LATERAL. This allows them to reference columns provided by preceding FROM items. (Without LATERAL, each subquery is evaluated independently and so cannot cross-reference any other FROM item.) Table functions appearing in FROM can also be preceded by the key word LATERAL, but for functions the key … Read more
The error happens because MySQL can index only the first N chars of a BLOB or TEXT column. So The error mainly happens when there is a field/column type of TEXT or BLOB or those belong to TEXT or BLOB types such as TINYBLOB, MEDIUMBLOB, LONGBLOB, TINYTEXT, MEDIUMTEXT, and LONGTEXT that you try to make a primary key or index. With full BLOB or TEXT without the length value, MySQL is unable to guarantee … Read more
Just write the order by is applied to the complete resultset
Take a look at the Operator Precedence in SQL Server (You’ve not specified that, but I’d imagine it’s the same for all RDBMS). What this means is that ANDs (without parenthesis) are evaluated before1 bind more tightly than ORs. So in your specific case, without the parenthesis, the conditions are: employe.service=service.code_serv AND employe.nom LIKE ‘A%’ OR employe.nom LIKE ‘B%’ … Read more
Try to cast it as a DATE