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- Usage of isnull function in sql
- The ISNULL() function in SQL checks whether an expression is NULL and returns the specified value. Usage is as follows: checks for a NULL value and returns a replacement value. Prevent divide-by-zero errors. Merge two fields to avoid duplication.
- SQL 691 2024-04-28 12:03:13
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- What do when and case mean in sql?
- WHEN and CASE in SQL are keywords used to check conditions and return specified values. WHEN is used to specify a condition. If the condition is true, the subsequent statement is executed; CASE is a control flow statement, which executes different statements according to the conditions that are met. The syntax is: CASE WHEN <condition1> THEN <result1> WHEN <condition2> THEN < result2> ... ELSE <default_result> END. The condition can be any valid SQL expression, example: SELECT CAS
- SQL 1002 2024-04-28 12:00:24
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- Usage of case statement in sql
- The CASE statement is used to return different values based on conditions. Syntax: CASE WHEN condition THEN result WHEN condition THEN result ... ELSE default_result END. Usage: 1. Specify a condition; 2. Return a result if the condition is true; 3. Use the ELSE clause to specify the default result when all conditions are false.
- SQL 1202 2024-04-28 11:54:15
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- What does case mean in sql
- The CASE statement is a SQL control structure that executes different SQL statements based on conditional expressions and returns results. The advantages include: providing conditional dynamic results, decomposing complex conditions, simplicity and efficiency.
- SQL 776 2024-04-28 11:48:15
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- Usage of casewhen in sql
- The CASE WHEN statement is used to return different values based on conditions. Its usage steps are: Specify conditions: Determine the conditions to be evaluated. Specifies the result: the value returned if the condition is true. Specify an ELSE clause: If no condition is true, a default value is returned (optional).
- SQL 840 2024-04-28 11:42:16
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- Usage of if statement in sql
- SQL IF statements are used to perform specific actions based on conditions. The syntax is: IF condition THEN expression 1 [ELSIF condition THEN expression 2]... [ELSE expression N] END IF; It allows you to dynamically modify queries or operations based on conditions, such as selecting specific columns, performing calculations, or updates /Insert data. Best practices include keeping conditions simple, avoiding nested IF statements, using ELSIF, and ensuring you always include an ELSE clause.
- SQL 492 2024-04-28 11:39:16
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- Conditional judgment statements in sql
- There are two common conditional statements in SQL: IF-ELSE statement and CASE statement. The IF-ELSE statement executes different statements depending on whether the condition is true or false, while the CASE statement executes the corresponding statement depending on whether the expression value matches different conditions.
- SQL 431 2024-04-28 11:36:13
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- How to calculate division with decimals in SQL
- The division operator in SQL automatically rounds. When decimals need to be retained, you can use the ROUND() function or explicitly convert the data type to floating point.
- SQL 789 2024-04-28 11:33:13
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- Function to query specific repeated data in the table in sql
- SQL functions for querying specific duplicate data in a table include: COUNT function: Counts the number of duplicate values. GROUP BY clause: Group data and calculate the values in each group. HAVING clause: Filters the results of aggregate queries.
- SQL 585 2024-04-28 11:30:23
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- How to check specific duplicate data in query table in sql
- After determining the duplicate columns that need to be checked, use the COUNT() and GROUP BY clauses to count the number of occurrences of unique values, and then use the HAVING clause to specify conditions by group aggregation function (such as COUNT()) to filter out specific duplicate data.
- SQL 1158 2024-04-28 11:27:17
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- How to express decimals in SQL
- In SQL, decimals are typically represented using the DECIMAL or NUMERIC data types. DECIMAL is used to represent decimals with fixed precision and scale, whereas NUMERIC allows variable precision and scale. Choosing the appropriate type depends on the precision and variability of decimals required.
- SQL 458 2024-04-28 11:24:13
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- The meaning of @ in sql
- The @ symbol in SQL represents a placeholder for a parameter, used to store dynamic or unspecified values. Specific usage scenarios include stored procedures/functions, dynamic SQL, and query parameterization.
- SQL 419 2024-04-28 11:14:32
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- The meaning of * in sql
- In SQL means all columns, it is used to simply select all columns in a table, the syntax is SELECT FROM table_name;. The advantages of using include simplicity, convenience and dynamic adaptation, but at the same time pay attention to performance, data security and readability. In addition, it can be used to join tables and subqueries.
- SQL 876 2024-04-28 11:09:16
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- What does ^ mean in sql
- The ^ symbol in SQL represents the bitwise XOR operation, which compares two binary bits and returns a new bit. The rules are: 0^0=0, 0^1=1, 1^0=1, 1^1=0. Uses include setting or removing flags, comparing values, and simple encryption and decryption.
- SQL 1112 2024-04-28 11:06:14
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- Usage of * in sql
- * in SQL is a wildcard character with the following usage: Query all columns: SELECT * FROM table_name; Alias all columns: SELECT * AS all_columns FROM table_name; Find specific values in the WHERE clause: SELECT FROM table_name WHERE LIKE '%value %';Use with aggregate functions: SELECT SUM(*) FROM table_name;
- SQL 449 2024-04-28 11:00:24
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