Therefore, for example the following create view statement: The syntax of the CASE statement is as follows: In PostgreSQL, the CASE statement is used for conditional expressions. The statements IF() and IFNULL() do not exist in PostgreSQL. IF and IFNULL (MySQL) / CASE (PostgreSQL) statements (conditional expressions) Below are two examples encountered in IMSMA NG views.ĪND (`customdefinedfield`.`label` = _utf8'CDF-Area Reduction MDU')ĪND (customdefinedfield.label = 'CDF-Area Reduction MDU')Ĭast(`geopoint`.`latitude` as char charset utf8) AS `lat` This is not the case in PostgreSQL and UTF-8 related syntax as used in MySQL does not work in PostgreSQL. In some (older) MySQL versions, UTF-8 was not the default character set and strings thus needed to be explicitly converted to UTF-8. If an column name in PostgreSQL is written with upper case but not enclosed into double quotes, it will be created in lower case in the database.ĬAST AS CHAR CHARSET utf8 and _utf8 (MySQL) For select rows where the device type is equal to 'xy', the syntax is the following. SELECT hazreducdeviceinfo.hazreduc_guid AS hazreduc_guid, SELECT `hazreducdeviceinfo`.`hazreduc_guid` AS `hazreduc_guid`, For example, the following create view statement: In PostgreSQL, this is also possible, but in this case the column name must be enclosed in double quotes. Similarly, in MySQL it is possible to define column names with a mix of upper and lower case as well as blanks and other special characters without any trouble. The single quote ` present in the MySQL queries is an artifact of the tool Navicat from which these queries have been extracted. WHERE imsmaenum.enumvalue = 'Progress Report' WHERE `imsmaenum`.`enumvalue` = 'progress report' Therefore, a create view statement like this: In PostgreSQL, the same query will return no result.
In MySQL it was possible to write:Īnd still get one row as result. For example, in the table IMSMAENUM, one out of many values in the column ENUMVALUE is Progress Report, with capital P and capital R. This means that strings need to be provided in exactly the way they are stored in the database. PostgreSQL, as opposed to MySQL, is case-sensitive. This can also be used as a tutorial for creating views in PostgreSQL, for IMSMA NG administrators who were used to creating them in MySQL. For reference, this section describes the main changes encountered. The country focal point is taking care of this. changed from MySQL syntax to PostgreSQL syntax. When upgrading from IMSMA NG 5.08.04 to 6.0, the database views need to be adapted, i.e. Most common changes in queries and views from MySQL to PostgreSQL PostgreSQL complies to ANSI SQL standards, whereas MySQL does not. For more details about using SQL statements in IMSMA NG import scripts contact your GICHD IM advisor. conditional expressions)įor more details about the PostgreSQL syntax it is advised to consult the official PostgreSQL documentation at. It is not possible to list all differences here, but the main ones encountered in the IMSMA NG world are highlighted below. However, there are some differences between the MySQL and PostgreSQL syntax. Both systems are relational database systems and using SQL, the Structured Query Language, as means for interacting with it. IMSMA NG version 6.0 is building on a PostgreSQL database management system, whereas previous IMSMA NG versions were built on a MySQL database. 2.3 IF and IFNULL (MySQL) / CASE (PostgreSQL) statements (conditional expressions).2.2 CAST AS CHAR CHARSET utf8 and _utf8 (MySQL).2 Most common changes in queries and views from MySQL to PostgreSQL.
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