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- How to use truncate in oracle
- The TRUNCATE command in Oracle is used to quickly delete all data in the table. It does not use transaction logs, is fast, and cannot be rolled back. It will reallocate the table space, retain the table definition, and reset the identity column. Compared with DELETE, TRUNCATE is faster, cannot be rolled back, and space will be reallocated.
- Oracle 461 2024-04-30 06:48:15
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- How to set numbers to retain integers in Oracle
- In Oracle, you can set a numeric field to retain only the integer part through the following steps: 1. Create a numeric field, specify the precision and decimal places as 0; 2. Insert a number with a decimal part; 3. Use the TO_NUMBER() function to convert the data type is an integer; 4. Update the data in the table; 5. Query the data again to verify whether the update is successful. These steps ensure that numeric fields retain only the integer portion.
- Oracle 690 2024-04-30 06:45:25
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- Usage of cast function in oracle
- The CAST function is used to explicitly convert a value to another data type with the syntax CAST(expression AS data_type). Usage examples include: convert numeric value to string, string to date, and string to number. Conversion options include numeric, character, date, and boolean types.
- Oracle 1148 2024-04-30 06:42:14
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- How to write date type data in oracle
- Oracle DATE type data represents date in the format YYYY-MM-DD, where YYYY represents the year, MM represents the month, ranging from 01 to 12, and DD represents the date, ranging from 01 to 31. For example, 2023-03-08 means March 8, 2023.
- Oracle 364 2024-04-30 06:39:12
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- How to use union in oracle
- The UNION operator in Oracle combines the result sets of multiple queries to create a new result set, retaining unique rows or all rows. It must ensure that the columns are of the same number and type and can be used in combination with ALL, INTERSECT, MINUS operators to further filter the results.
- Oracle 422 2024-04-30 06:36:14
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- The difference between union and union all in oracle
- The difference between UNION and UNION ALL in Oracle is the way duplicate rows are handled. UNION removes duplicate rows and returns only distinct rows; UNION ALL retains all rows, including duplicates.
- Oracle 1090 2024-04-30 06:33:14
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- How to use the replacement function in oracle
- Three replacement functions are provided in Oracle: REPLACE, TRANSLATE, and REGEXP_REPLACE. The REPLACE function replaces a specific substring, the TRANSLATE function replaces a set of characters, and the REGEXP_REPLACE function uses regular expressions for substring replacement.
- Oracle 863 2024-04-30 06:30:26
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- How to use unpivot in oracle
- The UNPIVOT operator converts row data in Oracle into column data for easier analysis and querying. It converts a data set containing multiple rows and columns into a new data set with an ID column representing the original row and a value column containing the values from the original column. The UNPIVOT syntax is: SELECT * FROM UNPIVOT(table_name) AS unpivoted_table[WHERE pivot_condition]. Benefits include simplified queries, improved performance, and support for pivoting. For example, you can convert sales quarter data into columns to easily analyze sales by product and quarter.
- Oracle 553 2024-04-30 06:27:20
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- How to use limit in oracle
- The LIMIT clause is used to limit the number of rows returned by an Oracle query, specifying the maximum number of rows to retrieve from the result set. Usage includes: LIMIT [number of rows]: Retrieve the specified number of rows. LIMIT [number of rows] OFFSET [number of rows]: Retrieve the specified row after skipping the specified row. LIMIT [number of rows] WHERE [condition]: Retrieve specified rows after filtering the conditions.
- Oracle 916 2024-04-30 06:21:14
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- How to write declare loop in oracle
- A DECLARE loop is an explicit iteration statement within an Oracle PL/SQL block that repeatedly executes a set of statements. Syntax: DECLARE - declare the data type of the loop variable BEGIN - initialize the loop variable LOOP - the loop body contains the statements to be executed EXIT WHEN - specify the exit loop condition END LOOPEND
- Oracle 964 2024-04-30 06:18:15
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- How to use group by in oracle
- The GROUP BY statement in Oracle is used to group data and aggregate summary values based on specified columns. The syntax is: SELECT aggregate function (column name), grouping column FROM table name GROUP BY grouping column. Features include grouping data with the same grouping column value, applying an aggregate function to each group to calculate a summary value, the grouping column is used to group the data, and the aggregate function is used to calculate the summary value.
- Oracle 487 2024-04-30 06:15:21
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- The difference between count1 and count* in oracle
- The difference between COUNT(1) and COUNT(*) in Oracle is: COUNT(1) ignores null values and only counts non-empty rows; COUNT(*) counts all rows, including null values; which function to choose depends on: whether there are null values value, prioritizing performance or consistency.
- Oracle 583 2024-04-30 06:12:15
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- Usage of trunc function in oracle
- The TRUNC function in Oracle is used to truncate a specified part of a date or number. It supports the following units: year, month, date, hour, minute, second. The syntax is TRUNC(expression, unit), expression is the expression to be truncated, and unit is the unit to be truncated.
- Oracle 517 2024-04-30 06:09:15
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- How to use while loop in oracle
- WHILE loop is used in Oracle to repeatedly execute a block of code when a specific condition is met. The syntax is: WHILE <condition> -- a block of code to be executed repeatedly END WHILE; The components include: Condition: a Boolean expression that determines whether the loop continues. Loop body: The block of code to be executed if the condition is true.
- Oracle 785 2024-04-30 06:06:14
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- What does ‖ mean in sql
- The | operator in SQL represents a logical OR operation that joins two Boolean values and returns a Boolean value: if both operands are TRUE, the result is TRUE. If both operands are FALSE, the result is FALSE. If one operand is TRUE and the other is FALSE, the result is TRUE. It is often used to combine conditions in the WHERE clause. It has lower priority and requires careful use of parentheses.
- SQL 515 2024-04-29 16:30:24
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