10 recommended articles about value processing

MySQL NULL value processing We already know that MySQL uses the SQL SELECT command and WHERE clause to read data from the data table, but when the query condition field provided is NULL, the command may not work properly. In order to handle this situation, MySQL provides three major operators: IS NULL: When the value of the column is NULL, this operator returns true. IS NOT NULL: When the column value is not NULL, the operator returns true. <=>: Comparison operator (different from = operator), returns true when the two compared values ​​are NULL. The conditional comparison operation on NULL is relatively special. You cannot use = NULL or ! =NULL finds NULL values ​​in the column. In MySQL, comparison of a NULL value with any other value (even NULL) always returns false, that is, NULL = NULL returns false. MySQL handles NULL using the IS NULL and IS NOT NULL operators. Using NULL values ​​in the command prompt The following examples assume numbers

1. MySQL NULL value processing example tutorial

Introduction: MySQL NULL value processing We already know that MySQL uses the SQLSELECT command and WHERE clause to read data in the data table, but when the query condition field provided is NULL, the The command may not work properly. In order to deal with...

2. Examples of date and time processing functions and numerical processing functions (Usage of data processing functions 2)

#Introduction: Date and time processing functions Date and time are stored in corresponding data types and special formats so that they can be sorted or sorted quickly and effectively. Filter and save physical storage space. Typically, applications do not use a format for storing dates and times, so date and time functions are always used to read and manipulate these values. For this reason, date and time functions play an important role in the MySQL language.

3. Freemarker The simplest example program

Introduction: The simplest example program of Freemarker is to create a template object through String and perform interpolation processing.

4. MySQL NULL value processing

# #Introduction: MySQL uses the SQL SELECT command and WHERE clause to read data in the data table, but when the query condition field provided is NULL, the command may not work properly. To handle this situation, MySQL provides three major operators: IS NULL: When the column value is NULL, this operator returns true. IS NOT NULL: When the column value is not NULL, the operator returns true. The conditional comparison operation on NULL is quite special. You cannot use...

5. User-Agent string uses the == operator in PHP for string comparison

Introduction: User-Agent string: User-Agent string uses the == operator in PHP for string comparison: A new article recently published on Greg Beaver's blog comparing strings in PHP with the == operator mentioned some issues worth noting when comparing strings with PHP's == operator. In some cases, PHP will convert numerical data (such as strings containing numbers, etc.) into numerical processing, and the == operator is one of them. When using the == operator to loosely compare two strings, PHP will convert the numeric-like string

6. Detailed explanation of Python magic methods

Introduction: This article mainly introduces the detailed explanation of Python magic methods. This article explains construction and initialization, magic methods for comparison, magic methods for numerical processing, ordinary arithmetic operators, etc. , Friends in need can refer to

7. SQL study notes seven functions number, date, type conversion, null value processing, case

Introduction: SQL study notes seven functions number, date, type conversion, null value processing, case usage instructions

8. SQL Server null value processing strategy [Recommended]

Introduction: Data integrity is the key point to ensure in any database system. No matter how well planned a system is, the problem of null data values ​​will always exist.

9. Redis source code analysis 2

# #Introduction: DICT data structure Dict is actually a hash table, but in Redis, there is already a data structure called Hash, so let’s rename the Hash table to Dict. . . Dict is the soul of Redis' key-value processing. No matter how large the amount of data is, it always maintains a time complexity of O(1) (excluding the case where the linked list under the bucket is very long). All keys saved globally,

10. How to handle the full threshold of ID identification when it appears in the distribution or merge agent in SQLSERVER

Introduction: ID identification appears in the distribution or merge agent in SQLSERVER Full threshold processing method sp_adjustpublisheridentityrange, ,

[Related Q&A recommendations]:

nginx - apaceh concurrency issues

The above is the detailed content of 10 recommended articles about value processing. For more information, please follow other related articles on the PHP Chinese website!