Codeigniter built-in Database Class usage instructions

In CodeIgniter, database usage is very frequent. You can use the database class that comes with the framework to perform database operations conveniently.

Initialize the database class to load and initialize the database class according to your database configuration: the code is as follows: this-> load-> database (); after being loaded, you can use it anywhere. The code for returning query results in the form of objects is as follows: $ query = $ this-> db-> query ('select name, title, email FROM my_table '); foreach ($ query-> result () as $ row) {echo $ row-> title; echo $ row-> name; echo $ row-> email ;} echo 'total Results :'. $ query-> num_rows (); the result () function above returns an array of objects. For example, the Code $ row-> title returns the query result in an array: $ query = $ this-> db-> query ('select name, title, email FROM my_table '); foreach ($ query-> result_array () as $ row) {echo $ row ['title']; echo $ row ['name']; echo $ row ['email '];} The above result_array () function returns an array with the lower mark. For example, $ row ['title'] returns a data object in the form of code: $ query = $ this-> db-> query ('select name FROM my_table LIMIT 1 '); $ row = $ query-> row (); echo $ row-> name; the row () function above returns an object. Example: $ row-> name array: Code: $ query = $ this-> db-> query ('select name FROM my_table LIMIT 1 '); $ row = $ query-> row_array (); echo $ row ['name']; The row_array () function above returns an array. For example, the $ row ['name'] insert data code is as follows: $ SQL = "INSERT INTO mytable (title, name) VALUES (". $ this-> db-> escape ($ title ). ",". $ this-> db-> escape ($ name ). ")"; $ this-> db-> query ($ SQL); echo $ this-> db-> affected_rows (); the database Configuration CodeIgniter has a configuration file for you to store the database connection value (username: username, password: password, database name: database name, etc ..). the configuration file is located in the following path: application/config/database. the php accessory file is stored in a multi-dimensional array in the following format: Code: $ db ['default'] ['hostname'] = "localhost "; $ Db ['default'] ['username'] = "root"; $ db ['default'] ['Password'] = ""; $ db ['default'] ['databas'] = "database_name"; $ db ['default'] ['dbdriver '] = "mysql "; $ db ['default'] ['dbprefix'] = ""; $ db ['default'] ['pconnect '] = TRUE; $ db ['default'] ['db _ debug'] = FALSE; $ db ['default'] ['cache _ on'] = FALSE; $ db ['default'] ['cachedir'] = ""; $ db ['default'] ['Char _ set'] = "utf8 "; $ db ['default'] ['dbcollat'] = "utf8_general_ci" The reason for using multi-dimensional arrays is to allow you to store multiple connection values at will. For example, if you run multiple environments (development: development, production: production, test: Testing, etc ..), you can establish independent connection groups for each environment and switch between groups directly. For example, to set up a "test" environment, you can do this: the code is as follows: $ db ['test'] ['hostname'] = "localhost "; $ db ['test'] ['username'] = "root"; $ db ['test'] ['Password'] = ""; $ db ['test'] ['databas'] = "database_name"; $ db ['test'] ['dbdriver '] = "mysql "; $ db ['test'] ['dbprefix'] = ""; $ db ['test'] ['pconnect '] = TRUE; $ db ['test'] ['db _ debug'] = FALSE; $ db ['test'] ['cache _ on'] = FALSE; $ db ['test'] ['cachedir'] = ""; $ db ['test'] ['Char _ set'] = "utf8 "; $ db ['test'] ['Dbcollat'] = "utf8_general_ci"; then, tell the system to use the "test" group. You can set the variable in the configuration file: Code: $ active_group = "test "; note: The name of "test" is arbitrary, which allows you to set it freely. Our main connection uses the name "default" by default. Of course, you can give it a more meaningful name based on your project. The Active Record class can be globally set using the $ active_record variable in the database configuration file (allow/disable TRUE/FALSE (boolean )). if you do not need this class, you can set this variable value to FALSE to reduce the consumption of computer resources during database class initialization. $ Active_record = TRUE; Note: Some CodeIgniter classes, such as Sessions, must be supported by Active Records when executing some functions. Parameter resolution: hostname-the host name of the database, which is usually on the local machine and can be expressed as "localhost ". username-username to connect to the database. password-password used to log on to the database. database-name of the database to be connected. dbdriver-database type. Such as mysql, ipvs, and odbc. It must be a lowercase letter. Dbprefix-the data table prefix when an Active Record query is run. It allows multiple CodeIgniter programs to be installed in a database. pconnect-TRUE/FALSE (boolean)-use persistent connection. db_debug-TRUE/FALSE (boolean)-displays database error information. cache_on-TRUE/FALSE (boolean)-whether the database query cache is enabled. For more information, see database cache. Cachedir-absolute path of the server where the cache directory is located in the database query. Char_set-character set used for communicating with the database. Dbcollat-character collation used to communicate with the database ). Port-database port number. Currently, it is only used for ipvs drivers. To use this value, you should add a line of code to the Database Configuration array.