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- The role of triggers in oracle
- Triggers in Oracle automate specific actions on database events, including: Ensuring data integrity Automating tasks Enhanced security Implementing business logic
- Oracle 1189 2024-05-09 21:57:20
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- The role of views in oracle
- A view in Oracle is a virtual table that provides a different perspective on data. Its main functions include: data abstraction, data security, data conversion, data integration and performance optimization. Benefits include: no storage space, data consistency, improved performance, enhanced security, and simplified data access. The disadvantages are: it may affect query performance, does not support data updates, and requires regular maintenance.
- Oracle 368 2024-05-09 21:54:16
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- How to use cursors in Oracle
- Cursors are a mechanism for traversing a query result set, allowing developers to process data row by row. Its usage includes: 1. Declare the cursor; 2. Open the cursor; 3. Extract data; 4. Get the row status; 5. Close the cursor. The advantages of cursors include row-by-row processing, reduced network traffic, and improved performance, but the disadvantages are resource consumption and potential problems.
- Oracle 283 2024-05-09 21:51:19
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- The role of cursor in Oracle
- Cursors are a mechanism in Oracle database to traverse result sets and process data row by row. They are mainly used for: traversing result sets, processing large data sets, updating or deleting data row by rows, transaction processing
- Oracle 509 2024-05-09 21:48:19
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- What are the types of triggers in Oracle?
- Oracle trigger types include: 1. INSERT (triggered when a record is inserted); 2. UPDATE (triggered when a record is updated); 3. DELETE (triggered when a record is deleted); 4. BEFORE (execute action before the event); 5. AFTER ( Execute the action after the event); 6. INSTEAD OF (replace the original event action); 7. ROW (apply the action only to specific rows); 8. STATEMENT (apply the action to the entire SQL statement); 9. DDL (when the DDL statement is executed Trigger); 10. System (created and maintained by Oracle).
- Oracle 938 2024-05-09 21:45:26
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- Statement for function return value in oracle
- In Oracle, the return value of a function is specified using the RETURN statement, which is located at the end of the function body and is used to return the result of the function calculation. The syntax of the RETURN statement is: RETURN value_expression; where value_expression is an expression that calculates and returns the function value.
- Oracle 687 2024-05-09 21:42:14
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- What are the common constraints in Oracle
- Common constraints in Oracle maintain data integrity and consistency through specific rules. These constraints include: 1. Primary key constraints: ensure that each row has a unique ID. 2. Foreign key constraints: associate a column in a table with a column in another table. 3. Unique constraint: Ensure that column values are unique and allow repetition in different rows. 4. Non-null constraint: columns are not allowed to accept null values. 5. Check constraints: Ensure that column values match specific conditions or expressions.
- Oracle 404 2024-05-09 21:39:19
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- How to see the number of occurrences of a certain character in Oracle
- To find the number of occurrences of a character in Oracle, perform the following steps: Get the total length of a string; Get the length of the substring in which a character occurs; Count the number of occurrences of a character by subtracting the substring length from the total length.
- Oracle 867 2024-05-09 21:33:17
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- Will Oracle interrupt index creation affect DML?
- No, interrupting index creation in Oracle will not affect the execution of DML statements because: Oracle uses a background process to create indexes and does not block DML operations. DML operations directly access the original data and are not affected by index creation.
- Oracle 1010 2024-05-09 21:27:14
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- How to use with in oracle
- The WITH statement improves the readability, reusability, and performance of Oracle queries by defining a temporary table expression (CTE): Define the CTE: WITH <CTE_name> AS (<subquery>) Use the CTE: SELECT ... FROM <CTE_name> ;Benefits include improved readability, avoiding repeated subquery writing, and optimizing performance through precomputation.
- Oracle 606 2024-05-09 21:24:23
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- Commands to solve lock table in oracle
- Oracle lock table problems can be solved with the following commands: View locked tables: SELECT * FROM V$LOCKED_OBJECTS; Release table locks: ALTER SYSTEM KILL SESSION '[session_id]'; Unlock or wait: COMMIT; or ROLLBACK; Force unlock ( Use with caution): ALTER TABLE [table_name] ENABLE ROW MOVEMENT; Modify session parameters: _optimizer_locks and _transaction_timeout; Detect lock type: SELECT *
- Oracle 1150 2024-05-09 21:18:18
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- Can subqueries be used in the with statement in Oracle?
- Oracle's with clause allows nested subqueries to enhance readability and maintainability, optimize performance, and simplify complex query structures by creating subquery aliases.
- Oracle 1120 2024-05-09 21:15:25
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- The difference between delete and drop in oracle
- Oracle's DELETE and DROP commands are used to delete data, but in different ways: DELETE deletes specific rows in a table that meet a condition and can recover deleted data. DROP deletes the entire table or other database objects, permanently deleting the data and making it irrecoverable.
- Oracle 831 2024-05-09 21:09:16
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- How to use intersect in oracle
- The INTERSECT operator is used to find rows that are common to two or more tables, that is, rows that appear in all tables at the same time. Usage is as follows: Each SELECT statement specifies a list of columns to compare. INTERSECT compares corresponding column values and includes the row if all values are equal. You can use the UNION clause to combine the results with INTERSECT results from other tables.
- Oracle 541 2024-05-09 21:06:19
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- Usage of ceil function in oracle
- The CEIL function in Oracle rounds a number to the nearest integer: Syntax: CEIL(number) Parameters: The number to be rounded Return value: Round to the nearest integer Purpose: Rounding, converting decimals to integers, Example of truncating the decimal part: CEIL(12.34) returns 13, CEIL(-45.67) returns -45
- Oracle 1080 2024-05-09 21:00:23
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