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mysql wildcard
Wildcards are a very useful tool in MySQL, which can help us query and filter data more conveniently. By using wildcards flexibly, we can quickly find data that meets specific conditions. When using wildcards, you need to pay attention to some precautions and try to reduce the scope of the query to improve query efficiency. At the same time, you can also explore some other functions for fuzzy queries, such as regular expressions. I hope this article will help you understand and use MySQL wildcards.
What are the uses of mysql wildcards?The usage of wildcard characters in MySQL includes percent sign (%) and underscore (_). Detailed introduction: 1. The wildcard percent sign (%) can query data starting with a specific character, query data ending with a specific character, and query data containing specific characters; 2. Underscore (_) can query the second character as a specific character. Character data, query the data when the third character is a specific character, query the data when the fourth character is a specific character.
How to automatically insert current date and time when inserting values in other columns in MySQL?In MySQL, by declaring the column as DEFAULTCURRENT_TIMESTAMP, we can automatically insert the current date and time into the column when inserting a value into another column. Example mysql>Createtabletesting ->( ->StudentNamevarchar(20)NOTNULL, ->RegDateTIMESTAMPDEFAULTCURRENT_TIMESTAMP&
How do we modify columns of MySQL table?By using the MODIFY keyword and the ALTERTABLE command, we can modify the columns of a MySQL table. The syntax is as follows; Syntax Altertabletable_nameMODIFYcolumn_name1datatype, MODIFYcolumn_name2datatype...MODIFYcolumn_nameNdatatype); Example In the following example, the size of the "Address" and "Grade" columns is modified with the help of the MODIFY keyword in the ALTER command. mysql>Altertablestudentmodif
Install MySQL on macOSLet us understand how to install MySQL on macOS. There is a package located in a disk image (.dmg) file, which needs to be mounted by double-clicking the icon in Finder. The next step is to mount the image and display its contents. Before installing MySQL, users must ensure that all MySQL server instances have been stopped. This can be done using the MySQL Management application on a macOS server, the preference pane, or using mysqladminshutdown on the command line. MySQL can be installed using the package installer. Let's see how to do this. Requires downloading a disk image (.dmg) file (a community version of which is also available). This will contain the MySQL soft
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