Dynamic SQL
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Dynamic SQL
Dynamic SQL refers to SQL queries that are constructed and executed at runtime. It allows flexible query building based on user input or application logic.
Syntax
EXECUTE IMMEDIATE 'SQL statement';
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What is Dynamic SQL?
- 1SQL built at runtime.
- 2Executed dynamically by DB engine.
- 3Allows flexible query generation.
- 4Used in stored procedures and scripts.
How Dynamic SQL Works
- 1Query is constructed as a string.
- 2Passed to execution engine.
- 3Compiled and executed at runtime.
- 4Can change based on input.
Types of Dynamic SQL
- 1Static dynamic SQL (predefined structure).
- 2Fully dynamic SQL (runtime generated).
- 3Prepared statements.
- 4Stored procedure dynamic queries.
Use Cases
- 1Search filters.
- 2Reporting systems.
- 3Multi-condition queries.
- 4Database automation tools.
Advantages
- 1Highly flexible queries.
- 2Reusable query logic.
- 3Supports complex conditions.
- 4Useful in admin systems.
Disadvantages
- 1SQL injection risk.
- 2Hard to debug.
- 3Performance overhead.
- 4Complex code maintenance.
Real-world
- 1Building flexible search filters.
- 2Generating dynamic reports.
- 3Multi-tenant applications.
- 4Custom query builders.
- 5Admin dashboards with variable conditions.
Common Mistakes
- 1Not using parameterized queries (SQL injection risk).
- 2Overusing dynamic SQL unnecessarily.
- 3Poor query validation.
- 4Complex debugging issues.
Best Practices
- 1Always use parameterized queries.
- 2Validate input before execution.
- 3Use dynamic SQL only when necessary.
- 4Keep queries simple and readable.
Quick Summary
- Dynamic SQL builds queries at runtime.
- Used for flexible query execution.
- Must be used carefully to avoid SQL injection.
- Supports prepared statements.
- Common in reporting and admin systems.
Interview Questions
Q1. What is dynamic SQL?
Answer: SQL queries that are built and executed at runtime.
Q2. What is the risk of dynamic SQL?
Answer: SQL injection attacks if not properly handled.
Q3. How to prevent SQL injection in dynamic SQL?
Answer: By using parameterized queries or prepared statements.
Q4. Where is dynamic SQL used?
Answer: In reporting systems and flexible query builders.
Q5. Is dynamic SQL faster?
Answer: Not always; it may have performance overhead.
Quiz
What is dynamic SQL?