current location：Home > Technical Articles > Database
- Direction：
- All web3.0 Backend Development Web Front-end Database Operation and Maintenance Development Tools PHP Framework Daily Programming WeChat Applet Common Problem Other Tech CMS Tutorial Java System Tutorial Computer Tutorials Hardware Tutorial Mobile Tutorial Software Tutorial Mobile Game Tutorial
- Classify：
-
- Usage of if else statement in sql
- IF-ELSE statements are used in SQL to perform different actions based on conditions. The basic syntax is: If the condition is true, execute statement 1. If the condition is false, statement 2 is executed. The condition is a Boolean expression and the statement can be any valid SQL statement.
- SQL 757 2024-04-28 10:00:20
-
- Usage of ifnull in sql
- The IFNULL function checks whether an expression is NULL and returns the specified default value if so, otherwise it returns the value of the expression. It prevents null values from causing errors, allows manipulation of null values, and improves the readability of queries. Usage includes: replacing null values with default values, excluding null values from calculations, and nested usage to handle multiple null value situations.
- SQL 1127 2024-04-28 09:57:17
-
- Usage of if else in sql
- The IF ELSE statement allows performing different actions based on conditions in a SQL query. It is used for conditional checking and executes the statement specified in THEN or ELSE based on the result. The syntax is: IF condition THEN operation 1 ELSE operation 2 END IF. Example: SELECT Product, IF(Product = 'Book', 'Book', 'Magazine') AS ProductType FROM Sales; Displays a "Book" or "Magazine" message based on the value of the Product column.
- SQL 1163 2024-04-28 09:54:14
-
- How many types of case syntax are there in sql?
- The CASE syntax in SQL provides a mechanism to conditionally select different expressions. It has four types: Simple: checks the condition to be true or false and returns the result. Search: Compare values to return matching results. Range: Returns results based on range conditions. NULLIF: Check whether the expressions are the same, if they are the same, return NULL.
- SQL 737 2024-04-28 09:48:14
-
- How to use case function in sql
- The SQL CASE function performs different operations by comparing expression results. Its syntax is: WHEN expression THEN result1WHEN expression THEN result2...[ELSE default_result]END
- SQL 876 2024-04-28 09:45:24
-
- What does case mean in sql
- The CASE statement is a SQL control flow statement that performs different actions based on specific conditions. The syntax is: CASE WHEN <expression1> THEN <result1> WHEN <expression2> THEN <result2> ... ELSE <default_result> END. It selects different blocks of code by checking a given expression and assigns grades, sets flags and performs complex queries as needed. CASE statements include simple CASE statements, search CASE statements, and value CA
- SQL 855 2024-04-28 09:42:15
-
- What does case when mean in sql
- The CASE WHEN statement is a conditional statement that evaluates multiple expressions and returns different values based on a condition. It evaluates the conditions from top to bottom, returning the value corresponding to the first true condition, or the optional default value if there is no true condition.
- SQL 391 2024-04-28 09:39:15
-
- Command to query duplicate data in sql
- The way to query duplicate data in SQL is to group the required columns using the GROUP BY clause. Use the HAVING clause to specify filter conditions for duplicate data.
- SQL 516 2024-04-28 09:36:15
-
- How to write query for duplicate data in sql
- In SQL, two ways to query for duplicate data are to use the GROUP BY clause to group the data and count the number of duplicates for each group. Use the EXCEPT clause to exclude a subquery that contains duplicate data from a subquery that contains all data.
- SQL 777 2024-04-28 09:30:20
-
- How to express not equal in sql
- In SQL, you can use the "<>" or "!=" symbols to express inequality. These two symbols are used to check whether a field is not equal to a specified "value".
- SQL 717 2024-04-28 09:27:12
-
- Usage of in in sql
- The IN operator in SQL checks whether a value is contained in a given value list: Syntax: column_name IN (value1, value2, ..., valueN) Returns true when the value in column_name matches any value in the list, otherwise Advantages of returning false: More efficient than other equality operators when checking multiple values
- SQL 1003 2024-04-28 09:24:14
-
- Usage of as in sql
- The AS keyword in SQL is used to specify aliases, including tables, columns or derived values: specify aliases for tables to facilitate multiple references. Assign aliases to columns to explicitly reference specific columns. Specify an alias for a derived value, referencing the result of a calculation or operation.
- SQL 747 2024-04-28 09:18:15
-
- Statements to modify table structure in sql
- The table structure can be modified through the ALTER TABLE statement. The specific operations are: add a column: ALTER TABLE table_name ADD column_name data_type; delete a column: ALTER TABLE table_name DROP COLUMN column_name; modify a column: ALTER TABLE table_name ALTER COLUMN column_name NEW_DATA_TYPE; add a constraint: ALTER TABLE table_name ADD CONSTRAINT constr
- SQL 673 2024-04-28 09:15:26
-
- command to delete table in sql
- Use the DELETE statement to delete data from a table. The syntax of the DELETE statement is: DELETE FROM table_name WHERE condition; where table_name is the table name and condition is an optional filter condition. If no condition is specified, all records in the table are deleted.
- SQL 1040 2024-04-28 09:09:12
-
- What does % mean in sql
- % in SQL represents a wildcard character, matching any number of characters in the string, which can appear at the beginning, middle, or end of the string, and is used for pattern matching in the LIKE clause.
- SQL 486 2024-04-28 09:06:11
Tool Recommendations
jQuery enterprise message form contact code
jQuery enterprise message form contact code is a simple and practical enterprise message form and contact us introduction page code.
form button
2024-02-29
HTML5 MP3 music box playback effects
HTML5 MP3 music box playback special effect is an mp3 music player based on HTML5 css3 to create cute music box emoticons and click the switch button.
Player special effects
2024-02-29
HTML5 cool particle animation navigation menu special effects
HTML5 cool particle animation navigation menu special effect is a special effect that changes color when the navigation menu is hovered by the mouse.
Menu navigation
2024-02-29
jQuery visual form drag and drop editing code
jQuery visual form drag and drop editing code is a visual form based on jQuery and bootstrap framework.
form button
2024-02-29
Organic fruit and vegetable supplier web template Bootstrap5
An organic fruit and vegetable supplier web template-Bootstrap5
Bootstrap template
2023-02-03
Bootstrap3 multifunctional data information background management responsive web page template-Novus
Bootstrap3 multifunctional data information background management responsive web page template-Novus
backend template
2023-02-02
Real estate resource service platform web page template Bootstrap5
Real estate resource service platform web page template Bootstrap5
Bootstrap template
2023-02-02
Simple resume information web template Bootstrap4
Simple resume information web template Bootstrap4
Bootstrap template
2023-02-02
Cute summer elements vector material (EPS PNG)
This is a cute summer element vector material, including the sun, sun hat, coconut tree, bikini, airplane, watermelon, ice cream, ice cream, cold drink, swimming ring, flip-flops, pineapple, conch, shell, starfish, crab, Lemons, sunscreen, sunglasses, etc., the materials are provided in EPS and PNG formats, including JPG previews.
PNG material
2024-05-09
Four red 2023 graduation badges vector material (AI EPS PNG)
This is a red 2023 graduation badge vector material, four in total, available in AI, EPS and PNG formats, including JPG preview.
PNG material
2024-02-29
Singing bird and cart filled with flowers design spring banner vector material (AI EPS)
This is a spring banner vector material designed with singing birds and a cart full of flowers. It is available in AI and EPS formats, including JPG preview.
banner picture
2024-02-29
Golden graduation cap vector material (EPS PNG)
This is a golden graduation cap vector material, available in EPS and PNG formats, including JPG preview.
PNG material
2024-02-27
Home Decor Cleaning and Repair Service Company Website Template
Home Decoration Cleaning and Maintenance Service Company Website Template is a website template download suitable for promotional websites that provide home decoration, cleaning, maintenance and other service organizations. Tip: This template calls the Google font library, and the page may open slowly.
Front-end template
2024-05-09
Fresh color personal resume guide page template
Fresh color matching personal job application resume guide page template is a personal job search resume work display guide page web template download suitable for fresh color matching style. Tip: This template calls the Google font library, and the page may open slowly.
Front-end template
2024-02-29
Designer Creative Job Resume Web Template
Designer Creative Job Resume Web Template is a downloadable web template for personal job resume display suitable for various designer positions. Tip: This template calls the Google font library, and the page may open slowly.
Front-end template
2024-02-28
Modern engineering construction company website template
The modern engineering and construction company website template is a downloadable website template suitable for promotion of the engineering and construction service industry. Tip: This template calls the Google font library, and the page may open slowly.
Front-end template
2024-02-28
