SQL

THIS WILL LET U SEE IF IT WORKS: root:~$ ** mysql -t -h sql -p -u username username < name of the file u want to check ** >>>>>>>>>>>>>>>>>>>>>>>> root:~$ **vi /etc/mysql/my.cnf** ( Edit your mysql config. file ) root:~$ **service mysql status** (shows if its running or not) root:~$ **service mysql start** root:~$ **service mysql stop** root:~$ **service mysql restart** >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> MySQL, PostgreSQL, Oracle, and SQL Server are all //relational// databases. They efficiently **store information in multiple tables that are linked together by relationships**. ( Hmm )

//or CRUD//. The most popular databases use Structured Query Language (SQL) to perform those operations subset of SQL to create your blueprints is called **Data Definition Language (DDL)**. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
 * Databases excel at four operations:**
 * 1. C**reating data
 * 2. R**eading data
 * 3. U**pdating data
 * 4.** **D**eleting data
 * primary key**: is the minimum set of information needed to uniquely identify a row in a database table. At first glance, the primary key for our book table could be the title
 * Database tables**: store information in rows and columns
 * columns** define are the definition (or template) that each row must follow. For a table that stores book information, we might have columns for **Title**, **Author**, **Date Published**, **Number of Pages**, **Price**, and **Description**

WARNING Be careful with //NULL// - NULL is not equal to "". It is //not// an empty string. It //cannot// be compared to something else. However, even though is nothing, you can tell if something IS NULL or IS NOT NULL. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
 * Data types can be split into three groups - text data types, numeric data types, and date/time data types**. Below is a table of some of the data types that MySQL supports.
 * ~ Group ||~ Data Type ||~ Description ||~ Sample ||
 * Text || CHAR || A fixed length of zero to 255 characters. Useful for data like state codes, which are always two characters long. || IL ||
 * Text || VARCHAR || A variable length of zero to 65535 characters. Useful for data whose length varies, but is always within a certain size range. Common examples are first or last names. || ILLINOIS ||
 * Text || TEXT || A variable length of up to 65535 characters. || Illinois is a great state. ||
 * Text || MEDIUMTEXT || A variable length of up to 16777215 characters. || This history of Illinois... ||
 * Text || LONGTEXT || A variable length of up to 4294967295 characters. || The longer history of Illinois... ||
 * Numeric || INT || Integer (whole) numbers. || 5 ||
 * Numeric || FLOAT || Floating decimal point numbers. || 5.15 ||
 * Numeric || DOUBLE || Decimal number, with a fixed number of digits before and after the decimal point. || 7.25 ||
 * Numeric || DECIMAL || Decimal number, with a fixed number of digits, just like DOUBLE. More accurate than FLOAT or DOUBLE, use for monetary values like prices. || 2.25 ||
 * Date || DATE || Year, month and day. || 2009-12-31 ||
 * Date || DATETIME || Year, month, day and time. || 2009-12-31 14:25:00 ||
 * Date || TIME || Time only. || 14:25:00 ||