Posts about MySQL
MySQL DELETE statement
May 15, 2021 21:00 0 Comment MySQL
MySQL DELETE statement, MySQL DELETE statement, Remove the data from the command line, Use the PHP script to delete the data, MySQL DELETE statement, You can use SQL's DELETE FROM command to delete records from mySQL data sheets., You can execute the command in a mysql?comman
MySQL index
May 15, 2021 21:00 0 Comment MySQL
Normal index, Normal index, Unique index, Use the ALTER command to add and remove indexes, Use the ALTER command to add and remove primary keys, The index information is displayed, The establishment of MySQL index is very important for the efficient operation of MySQL, and index can greatly improve the retrieval speed of MySQL.,
MySQL ALTER command
May 15, 2021 21:00 0 Comment MySQL
MySQL ALTER command, MySQL ALTER command, Delete, add, or modify table fields, Modify the field type and name, ALTER TABLE's effect on Null values and default values, Modify the field default, Modify the table name, MySQL ALTER command, When we need to modify the data table name or modify the data table field, we need to use the MySQL ALTER command., Before we beg
MySQL transactions
May 15, 2021 21:00 0 Comment MySQL
MySQL transactions, MySQL transactions, MySQL transactions, MySQL transactions are primarily used to process data with high operational volumes and complexity., For example, in a personnel m
MySQL regular expression
May 15, 2021 21:00 0 Comment MySQL
MySQL regular expression, MySQL regular expression, MySQL regular expression, In the previous sections we learned that MySQL can, be fuzzy by LIKE ...%., MySQL also supports matching of other regular ex
MySQL NULL value processing
May 15, 2021 21:00 0 Comment MySQL
MySQL NULL value processing, MySQL NULL value processing, Use the NULL value in the command prompt, The NULL value is processed using a PHP script, MySQL NULL value processing, We already know that MySQL uses SQL SELECT commands and WHERE clauses to read data in the data table, but the command may
Use of MySQL connections
May 15, 2021 21:00 0 Comment MySQL
Use of MySQL connections, Use of MySQL connections, Use INNER JOIN in command prompts, MySQL LEFT JOIN, MySQL RIGHT JOIN, Use JOY in PHP scripts, Use of MySQL connections, In previous chapters, we've learned that reading data from a table is relatively simple, but in real applications you often
MySQL grouping
May 15, 2021 21:00 0 Comment MySQL
MySQL GROUP BY statement, MySQL GROUP BY statement, Example demonstration, MySQL GROUP BY statement, GROUP BY statements group result sets based on one or more columns., We can use COUNT, SUM, AVG, etc. on the grouped columns
MySQL sorting
May 15, 2021 21:00 0 Comment MySQL
MySQL sorting, MySQL sorting, Use the ORDER BY clause in command prompts, Use the ORDER BY clause in PHP scripts, MySQL sorting, We know that SQL SELECT statements are used to read data from mySQL tables., If we need to sort the read data, we can use MySQL's ORDER
MySQL LIKE clause
May 15, 2021 21:00 0 Comment MySQL
MySQL LIKE clause, MySQL LIKE clause, Use the LIKE clause in the command prompt, Use the LIKE clause in PHP scripts, MySQL LIKE clause, We know that SQL SELECT commands are used in MySQL to read data, and we can use the WHERE clause in SELECT statements to get the sp
MySQL temporary table
May 15, 2021 22:00 0 Comment MySQL
MySQL temporary table, MySQL temporary table, Delete the MySQL temporary table, MySQL temporary table, MySQL temporary tables are useful when we need to save some temporary data. T, emporary tables are only visible on the current
MySQL copies the table
May 15, 2021 22:00 0 Comment MySQL
MySQL copies the table, MySQL copies the table, MySQL copies the table, If we need to fully copy MySQL data tables, including table structures, indexes, default values, and so on. I, f you only use,
MySQL metadata
May 15, 2021 22:00 0 Comment MySQL
MySQL metadata, MySQL metadata, Gets the number of records affected by the query statement, A list of databases and data tables, Gets server metadata, MySQL metadata, You may want to know three things about MySQL:, Query result information:, Select, UPDATE, or DELETE statements affect the number of r
The MySQL sequence is used
May 15, 2021 22:00 0 Comment MySQL
The MySQL sequence is used, The MySQL sequence is used, Use AUTO_INCREMENT, Gets AUTO_INCREMENT value, Reset the sequence, Sets the start value of the sequence, The MySQL sequence is used, MySQL sequence is a set of integers: 1, 2, 3, ..., since a data table can only have one field self-adding primary key, if
MySQL processes duplicate data
May 15, 2021 22:00 0 Comment MySQL
MySQL processes duplicate data, MySQL processes duplicate data, Prevent duplicate data from appearing in the table, Query duplicate records, Statistics duplicate data, Filter duplicate data, Delete duplicate data, MySQL processes duplicate data, Some MySQL data tables may have duplicate records, and in some cases we allow duplicate data to exist, but sometimes w