MySQL trim usage example

in SQL statement or trim it in php, I thought it will be better to do it in MySQL in this case. MySQL ... provided the handy function trim to do it. Here is how to use it. mysql> SELECT TRIM(' a string ... '); -- delete leading and trailing whitespace -> 'a string' mysql> SELECT TRIM ... ' mysql> SELECT TRIM(BOTH 'x' FROM 'xxxmystringxxx'); -- delete specified leading and trailing

MySQL How to import data from SQL file

Suppose you exported a SQL file from phpMyAdmin and you want to import to a local MySQL ... are already contained The command to import the file is mysql -uroot -p databasename < post.sql ... ) at line 53: Duplicate entry '91' for key 1 And then import the file, the table creation statements ... instance. The data comes from a table post. You need to first delete the old table from your local

MyISAM vs InnoDB what's the difference and which one to use?

and consistent which MyISAM can't help you. [Table level locking vs row level locking] One ... of the most used arguments against MyISAM is it uses table level locking and InnoDB uses row level locking ... load and InnoDB is good at write heavy load] Why MyISAM is widely used even it has so little ... MyISAM and InnoDB are two most popular storage engines for MySQL database. Understand

MySQL InnoDB not row level locking for all queries

One misconception people have about MyISAM and InnoDB is InnoDB use row level locking ... and MyISAM use table level locking. It's true that MyIASM has no support row level locking, but InnoDB only ... support row level locking in particular circumstances. InnoDB uses Record locks for row level ... locking, which means it set locks on index record. Only when the query using index, the row level

How to check InnoDB support

InnoDb is a storage engine to MySQL table, it support transaction and row level locking ... to check whether the InnoDB engine is disabled, the first is command show engines as follows: mysql ... distributed version, the InnoDB is disabled by default, so you better check it before do any ... . There commands in MySQL only works for InnoDB engine such as for update and start transaction. When I want

Understanding locks in MySQL

There various type of locks in MySQL database implementation. It's critical ... choices for example which storage engine to use? [Shared locks] Also called read locks, because ... locks. When a thread acquire shared lock on a table, other threads can read it but can't write ... write operations. [Exclusive locks] Also called write locks, when a write operation is issued

The advantages and disadvantages of MySQL

and disadvantages of MySQL in this post. [MySQL is widely used] Although the accurate number ... , MySQL also has some disadvantages. [Stored procedure and trigger is limited] Compare ... MySQL is an Open Source, high performance , feature-rich relational database management ... software, it's been used in various environments. MySQL used to be the first choice for open source

MySQL export table definition and create index tips

Sometimes we need to quickly rebuild existed table structure. Mysql provided mysqldump options to facilitate this.

Or you can export single table in a database.

MySQL add index example

I find my program gets slower and slower when the data grows. The program is a web page crawler, when it downloaded a page and save it to MySQL database, it saved the url of the page at the same time.

When the crawler visit the target site again, it may catches the already grabbed url. The program has to search in the database to determine whether the url is already existed. A simple SQL query can do the trick.

When the crawler visit the target site again, it may catches the already grabbed url. The program has to .

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