Unknown column in ‘field list’ error on MySQL Update query
Try using different quotes for “y” as the identifier quote character is the backtick (“`”). Otherwise MySQL “thinks” that you point to a column named “y”. See also MySQL 5 Documentation
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Unknown column in ‘field list’ error on MySQL Update query
Try using different quotes for “y” as the identifier quote character is the backtick (“`”). Otherwise MySQL “thinks” that you point to a column named “y”. See also MySQL 5 Documentation
Inserting multiple rows in a single SQL query? [duplicate]
In SQL Server 2008 you can insert multiple rows using a single SQL INSERT statement. For reference to this have a look at MOC Course 2778A – Writing SQL Queries in SQL Server 2008. For example:
What is an index in SQL?
An index is used to speed up searching in the database. MySQL have some good documentation on the subject (which is relevant for other SQL servers as well): http://dev.mysql.com/doc/refman/5.0/en/mysql-indexes.html An index can be used to efficiently find all rows matching some column in your query and then walk through only that subset of the table to … Read more
SQL WITH clause example [duplicate]
The SQL WITH clause was introduced by Oracle in the Oracle 9i release 2 database. The SQL WITH clause allows you to give a sub-query block a name (a process also called sub-query refactoring), which can be referenced in several places within the main SQL query. The name assigned to the sub-query is treated as … Read more
ORA-00904: invalid identifier
Your problem is those pernicious double quotes. Oracle SQL allows us to ignore the case of database object names provided we either create them with names all in upper case, or without using double quotes. If we use mixed case or lower case in the script and wrapped the identifiers in double quotes we are … Read more
What is a stored procedure?
Stored procedures are a batch of SQL statements that can be executed in a couple of ways. Most major DBMs support stored procedures; however, not all do. You will need to verify with your particular DBMS help documentation for specifics. As I am most familiar with SQL Server I will use that as my samples. … Read more
Case in Select Statement
I have an SQL statement that has a CASE from SELECT and I just can’t get it right. Can you guys show me an example of CASE where the cases are the conditions and the results are from the cases. For example: where the results show
Selecting COUNT(*) with DISTINCT
Count all the DISTINCT program names by program type and push number DISTINCT COUNT(*) will return a row for each unique count. What you want is COUNT(DISTINCT <expression>): evaluates expression for each row in a group and returns the number of unique, non-null values.
What is the difference between UNION and UNION ALL?
UNION removes duplicate records (where all columns in the results are the same), UNION ALL does not. There is a performance hit when using UNION instead of UNION ALL, since the database server must do additional work to remove the duplicate rows, but usually you do not want the duplicates (especially when developing reports). UNION Example: Result: UNION ALL example: Result: