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  1. Richard To
    Thread

    How to tune a SQL that cannot be tuned?

    Some mission-critical SQL statements are already reached their maximum speed within the current indexes configuration. It means that those SQL...
    Thread by: Richard To, Sep 13, 2021, 0 replies, in forum: Oracle
  2. Richard To
    Thread

    How to Tune SQL Statement with CASE Expression for SQL Server II?

    We have discussed how to tune a CASE expression SQL with hardcoded literals in my last blog: How to Tune SQL Statement with CASE Expression for...
    Thread by: Richard To, Aug 19, 2021, 0 replies, in forum: SQL Server
  3. Richard To
    Thread

    How to Tune SQL Statement with CASE Expression for SQL Server I?

    Here the following is a simple SQL statement with a CASE expression syntax. SELECT * FROM EMPLOYEE WHERE CASE when emp_id < 1001000 then 'Old...
    Thread by: Richard To, Jul 19, 2021, 0 replies, in forum: SQL Server
  4. Richard To
    Thread

    How to Tune SQL Statements to Run SLOWER… but Make Users Feel BETTER (MySQL)?

    Your end-users may keep on complaining about some functions of their database application are running slow, but you may found that those SQL...
    Thread by: Richard To, May 19, 2021, 0 replies, in forum: MySQL
  5. Richard To
    Thread

    How to Tune Bad Performance SET ROWCOUNT SQL Statements for SQL Server?

    Some SQL statements will be running very slow after SET ROWCOUNT or TOP is used. SET ROWCOUNT and TOP are used to tell SQL Server to select a...
    Thread by: Richard To, Apr 28, 2021, 0 replies, in forum: SQL Server
  6. Richard To
    Thread

    How to Tune SQL Statement with IN Operator with an Expression List for SQL Server?

    The following is an example shows a SQL statement with an IN List expression. The SQL retrieves records from EMPLOYEE table that EMP_DEPT should...
    Thread by: Richard To, Apr 7, 2021, 0 replies, in forum: SQL Server
  7. Richard To
    Thread

    How to Tune SQL Statements with CONCAT Operator for MySQL?

    There may be some business requirements that need to compare concatenate strings and column with a given unknown length of the bind variable....
    Thread by: Richard To, Feb 19, 2021, 0 replies, in forum: MySQL
  8. Richard To
    Thread

    How to Tune SQL statement with Transitive Dependency Improvement for MySQL?

    The following is an example shows a SQL statement with two conditions “emp_dept=dpt_id and emp_dept<'L'” . select * from employee, department...
    Thread by: Richard To, Jan 22, 2021, 0 replies, in forum: MySQL
  9. Richard To
    Thread

    How to Tune SQL Statement with Driving Path Control for MySQL?

    The following is an example shows a SQL statement with two potential table join paths. “Employee to Department” and “Department to Employee” are...
    Thread by: Richard To, Jan 4, 2021, 0 replies, in forum: MySQL
  10. Richard To
    Thread

    How to Tune SQL with Exists Operator in Certain Environment for Oracle?

    Here is an example SQL that retrieves data from EMPLOYEE table with “emp_id < 710000” and employee’s department code exists in DEPARTMENT table....
    Thread by: Richard To, Dec 18, 2020, 0 replies, in forum: Oracle
  11. Richard To
    Thread

    How to Tune SQL with SEMI JOIN by Hints INDEX_DESC Injection for Oracle?

    Semi-join is introduced in Oracle 8.0. It provides an efficient method of performing a WHERE EXISTS or WHERE IN sub-queries. A semi-join returns...
    Thread by: Richard To, Dec 6, 2020, 0 replies, in forum: Oracle
  12. Richard To
    Thread

    How to Tune SQL Statement with Multiple Union in Subquery for MySQL?

    The following is an example shows a SQL statement with two union operator in a subquery. The SQL retrieve records from EMPLOYEE table that EMP_ID...
    Thread by: Richard To, Nov 30, 2020, 0 replies, in forum: MySQL
  13. Richard To
    Thread

    How to Tune SQL with LIKE '%ROGER%' SQL Statements for Oracle?

    The LIKE is a logical operator that determines if a character string matches a specified pattern. A pattern may include regular characters and...
    Thread by: Richard To, Nov 26, 2020, 0 replies, in forum: Oracle
  14. Richard To
    Thread

    How to Tune Delete SQL statement with subqueries for MySQL?

    The following is an example shows a DELETE SQL statement with subquery. The SQL delete records from emp_subsidiary that should satisfy with three...
    Thread by: Richard To, Nov 23, 2020, 0 replies, in forum: MySQL
  15. Richard To
    Thread

    How to Tune SQL Statement with Multiple OR Subqueries for Oracle?

    Here the following is SQL statement with multiple OR subqueries. SELECT * FROM employee WHERE emp_id IN (SELECT emp_id FROM emp_subsidiary where...
    Thread by: Richard To, Nov 16, 2020, 0 replies, in forum: Oracle
  16. Richard To
    Thread

    How to Tune SQL with “Group By” statement?

    The following is an example shows a SQL statement with “Group by” expression. The SQL retrieve the sum of historical salary from table...
    Thread by: Richard To, Nov 10, 2020, 0 replies, in forum: MySQL
  17. Richard To
    Thread

    How to Tune SQL Statement with CASE Express for Oracle?

    Here the following is a simple SQL statement with a CASE expression syntax. SELECT * FROM employee WHERE CASE WHEN emp_salary< 1000 THEN 'low'...
    Thread by: Richard To, Nov 2, 2020, 0 replies, in forum: Oracle
  18. Richard To
    Thread

    How to Tune SQL Statement with “< All (subquery)” Operator for Oracle?

    Here the following is a simple SQL statement with a “< ALL (Subquery)” syntax. SELECT * FROM employee a WHERE a.emp_salary <ALL(SELECT...
    Thread by: Richard To, Oct 26, 2020, 0 replies, in forum: Oracle
Showing results 1 to 18 of 18
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