Editing Migrate database engine from MySQL to SQLite

Steps of migration database engine from MySQL to SQLite

== Steps of migration database engine from MySQL to SQLite ==

# Migrate database data from MySQL to SQLite using the [[SQLite management software]]
# Modify the scripts of database connection and SQL query syntax because some MySQL functions are not compatible in SQLite
# Testing the scripts

== Notes of modification of scripts ==
* Remove database name from SQL query: SQLite will consider the database name as table name
* In MySQL, string are able to quoted with single quote symbol {{kbd | key=<nowiki>'</nowiki>}} or double quote symbol {{kbd | key=<nowiki>"</nowiki>}}. In SQLite the string quoted with double quote symbol will be considered as '''column name'''! It will cause the problem: "no such column: xxx"
* Replace the following functions
** Replace MySQL [https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_char-length CHAR_LENGTH] function with SQLite [https://www.sqlitetutorial.net/sqlite-functions/sqlite-length/#targetText=SQLite%20Length,returns%20the%20number%20of%20bytes. Length] function<ref>[https://github.com/owncloudarchive/mozilla_sync/issues/47 sqlite does not have CHAR_LENGTH function · Issue #47 · owncloudarchive/mozilla_sync]</ref>
** Replace MySQL {{kbd | key=IF}} function with SQLite {{kbd | key=CASE}} function<ref>[https://www.sqlitetutorial.net/sqlite-case/ SQLite CASE Expression: Simple CASE & Search CASE]</ref>
** Replace MySQL {{kbd | key=LOCATE}} function<ref>[https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_locate MySQL :: MySQL 8.0 Reference Manual :: 12.5 String Functions and Operators]</ref> with SQLite INSTR {{kbd | key=CASE}} function<ref>[https://www.sqlitetutorial.net/sqlite-functions/sqlite-instr/ SQLite INSTR]</ref>

<pre>
-- MySQL
LOCATE(substr,str), LOCATE(substr,str,pos)

-- SQLite
INSTR(string, substring);
</pre>

* Other functions are not supported such as: SET, Truncate<ref>[https://www.runoob.com/sqlite/sqlite-truncate-table.html SQLite Truncate Table | 菜鸟教程]</ref>, INGORE

== References ==
<references />

[[Category:Data Science]]
[[Category:MySQL]]
[[Category:SQLite]]
[[Category:Tool]]