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  • Question

  • A subquery in an sql select statement.


  • Correct Answer
  • A Subquery or Inner query or a Nested query is a query within another SQL query and embedded within the WHERE clause Subqueries are most frequently used with the SELECT statement The basic syntax is as follows:: SELECT column_name [, column_name ] FROM table1 [, table2 ] WHERE column_name OPERATOR (SELECT column_name [, column_name ] FROM table1 [, table2 ] [WHERE]) A subquery is used to return data that will be used in the main query as a condition to further restrict the data to be retrieved Subqueries can be used with the SELECT, INSERT, UPDATE, and DELETE statements along with the operators like =, <, >, >=, <=, IN, BETWEEN, etc There are a few rules that subqueries must follow ? 1 Subqueries must be enclosed within parentheses 2 A subquery can have only one column in the SELECT clause, unless multiple columns are in the main query for the subquery to compare its selected columns 3 An ORDER BY command cannot be used in a subquery, although the main query can use an ORDER BY The GROUP BY command can be used to perform the same function as the ORDER BY in a subquery 4 Subqueries that return more than one row can only be used with multiple value operators such as the IN operator 5 The SELECT list cannot include any references to values that evaluate to a BLOB, ARRAY, CLOB, or NCLOB 6 A subquery cannot be immediately enclosed in a set function 7 The BETWEEN operator cannot be used with a subquery However, the BETWEEN operator can be used within the subquery 

    • Tags: Analyst, Database Administrator, IT Trainer, Project Manager

    Oracle Certification problems

    Search Results

    • 1. Can?t update primary table?s primary key if row being modified has related rows in secondary table once referential integrity is enforced

    • Options
    • A. TRUE
    • B. FALSE
      • Discuss
    • 2. Breaking of relationships is allowed once referential integrity on a database is enforced

    • Options
    • A. TRUE
    • B. FALSE
      • Discuss
    • 3. STUFF and REPLACE are used to replace characters in a string

    • Options
    • A. TRUE
    • B. FALSE
      • Discuss
    • 4. Multiple users can share a local temporary table

    • Options
    • A. TRUE
    • B. FALSE
      • Discuss
    • 5. Copying the logs on the standby/backup server is an operation of Log Shipping

    • Options
    • A. TRUE
    • B. FALSE
      • Discuss
    • 6. The SQL keyword BETWEEN is used:

    • Options
    • A. for ranges
    • B. as a wildcard
    • C. to limit the columns displayed
    • D. All the above
      • Discuss
    • 7. Data integrity constraints are used to

    • Options
    • A. Ensure that duplicate records are not entered into the table
    • B. Prevent users from changing the values stored in the table
    • C. Control who is allowed access to the data
    • D. Improve the quality of data entered for a specific property like table column
      • Discuss
    • 8. What is an Extension of Entity Type?
    • Discuss
    • 9. Which packages contain the JDBC classes?

    • Options
    • A. java.sql
    • B. java.sl
    • C. java.jd
    • D. java.jdbc
      • Discuss
    • 10. A statistical method for identifying which factors may influence specific variables of a product or process under development or in production is called

    • Options
    • A. cost benefit analysis.
    • B. sensitivity analysis.
    • C. cost of quality analysis.
    • D. design of experiments.
      • Discuss

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