MySQL

When it comes to overall performance, it's important to remember that the #1 contributor is always a good database design. The second highest contributor to performance is well-tuned SQL code.

But a better day has come along in MySQL 5.0.37 with the inclusion of the SQL Profiling utility. This interactive diagnostic aid allows a developer or DBA to gain insight into where a set of SQL code spends its time and the resources it is using.

Each parameter is an IN parameter by default. To specify otherwise for a parameter, use the keyword OUT or INOUT before the parameter name.

Specifying a parameter as IN, OUT, or INOUT is valid only for a PROCEDURE. (FUNCTION parameters are always regarded as IN parameters.)

The function expects to be given a string containing a US English date format and will try to parse that format into a Unix timestamp

echo strtotime("now"), "\n";echo strtotime("10 September 2000"), "\n";echo strtotime("+1 day"), "\n";echo strtotime("+1 week"), "\n";echo strtotime("+1 week 2 days 4 hours 2 seconds"), "\n";echo strtotime("next Thursday"), "\n";echo strtotime("last Monday"), "\n";

想要预载入缓存，可以使用 LOAD INDEX INTO CACHE 语句。如下语句预载入了表 t1 和 t2 的索引节点(区块)：

MATCH (patient_1_question.terms) AGAINST ('+$term_1 +$term_2 +$term_3 +$term_4' IN BOOLEAN MODE

当前week的第一天： select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 1 DAY) 当前week的最后一天： select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) - 5 DAY) 前一week的第一天： select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 8 DAY) 前一week的最后一天： select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 2 DAY) 前两week的第一天： select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 15 DAY) 前两week的最后一天： select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) + 9 DAY)

当前month的第一天： SELECT concat(date_format(LAST_DAY(now()),'%Y-%m-'),'01') 当前month的最后一天： SELECT LAST_DAY(now()) 前一month的第一天： SELECT concat(date_format(LAST_DAY(now() - interval 1 month),'%Y-%m-'),'01') 前一month的最后一天： SELECT LAST_DAY(now() - interval 1 month) 前两month的第一天： SELECT concat(date_format(LAST_DAY(now() - interval 2 month),'%Y-%m-'),'01') 前两month的最后一天： SELECT LAST_DAY(now() - interval 2 month)

当前quarter的第一天： select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-3 month),'%Y-%m-'),'01') 当前quarter的最后一天： select LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-1 month) 前一quarter的第一天： select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-6 month),'%Y-%m-'),'01') 前一quarter的最后一天： select LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-4 month) 前两quarter的第一天： select concat(date_format(LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-9 month),'%Y-%m-'),'01') 前两quarter的最后一天： select LAST_DAY(MAKEDATE(EXTRACT(YEAR FROM CURDATE()),1) + interval QUARTER(CURDATE())*3-7 month)

Fixing these two misfeatures is exactly the purpose of this article. Using features introduced in MySQL 5.0 and 5.1, it is possible to build a replication system where all nodes act as master and slave at the same time, with a built-in fail-over mechanism.

If you want multiple databases, you can either set up different users for them or grant their privileges to the same user.

mysql_stmt_send_long_data()

Return Values Zero if the data is sent successfully to server. Non-zero if an error occurred.

mysql_stmt_bind_param()

Return Values Zero if the bind operation was successful. Non-zero if an error occurred.

will not speed the process, but it will allow the live application to use the mysql database as normal without locking any tables and preventing the application to change the database.

Declarations must follow a certain order. Cursors must be declared before declaring handlers, and variables and conditions must be declared before declaring either cursors or handlers.

DECLARE is allowed only inside a BEGIN ... END compound statement and must be at its start, before any other statements.

The --master-data option above locks all of the tables during the dump to prevent data from being changed, but allows users to continue reading the tables. With exclusive access, this feature isn't necessary. However, this option also adds a few lines like the following to the end of the dump file: