UPDATE events SET start = SYS_EXTRACT_UTC(FROM_TZ(start, 'Europe/Brussels'));

You get a more generic variant using the AT TIME ZONE clause:

UPDATE events SET start = FROM_TZ(start, 'Europe/Brussels') AT TIME ZONE 'America/Denver';

I’m trying to move selected data from one table to another. The following works apart from the destination table is not incrementing the ID (I’m not using auto increment for that field).
How can I increase the value of field_1_id for each select > insert? I’m guessing SQL doesn’t loop through each SELECT match an insert correspondingly?

Here is a possible answer: (Don’t forget to wrap these queries in a transaction if your MySQL Engine supports it)

-- Some demo tables (and data)
-- CREATE TABLE table1 (id INT(10), name VARCHAR(20), PRIMARY KEY(id));
-- CREATE TABLE table2 (id INT(10), name VARCHAR(20), PRIMARY KEY(id));
-- INSERT INTO table1 VALUES (1, "tim"), (2, "mike");

SET @id := (SELECT MAX(id) + 1 FROM table2);   
INSERT INTO table2 SELECT @id := @id  + 1, table1.name FROM (SELECT @id) AS id, table1 AS table1; 

CREATE TYPE LIST_NUMBER AS TABLE OF NUMBER(10);
/

Next thing to do is add a custom type and function header to the package specification:

PACKAGE TIMVW.TESTPACKAGE AS
 
TYPE CRSR_REF IS REF CURSOR;
TYPE ARR_IDS IS TABLE OF TEST.TEST_ID%Type INDEX BY BINARY_INTEGER;

PROCEDURE GET_TESTS
(
 P_IDS        IN        ARR_IDS,
 P_CURSOR  OUT     CRSR_REF
);
END;

And offcourse we have to implement the function in the body:

PROCEDURE GET_TESTS
(
 P_IDS       IN        ARR_IDS,
 P_CURSOR OUT     CRSR_REF
)

AS

V_IDS LIST_NUMBER := LIST_NUMBER();

BEGIN

V_IDS.EXTEND(P_IDS.COUNT);
FOR i IN P_IDS.FIRST .. P_IDS.LAST LOOP
  V_IDS(i) := P_IDS(i);
END LOOP;

OPEN       P_CURSOR FOR
SELECT    
              TEST.TEST_ID,
              TEST.NAME,
              TEST.TYPE_CODE
FROM
              TEST
WHERE
              TEST_ID IN (SELECT * FROM TABLE(V_IDS))
ORDER BY
              TEST.TEST_ID ASC;
END;

Now that we have done all this we can consume the function from our client code:

using (OracleConnection conn = new OracleConnection("User Id=u;password=p;Data Source=ORCL"))
{
 conn.Open();

 OracleCommand command = conn.CreateCommand();
 command.CommandType = CommandType.StoredProcedure;

 command.CommandText = "TIMVW.TESTPACKAGE.GET_TESTS";
 command.Parameters.Add("P_IDS", OracleDbType.Int32, new int[] { 1, 2, 3 }, ParameterDirection.Input);
 command.Parameters["P_IDS"].CollectionType = OracleCollectionType.PLSQLAssociativeArray;
 command.Parameters.Add("P_CURSOR", OracleDbType.RefCursor, ParameterDirection.Output);

 OracleDataReader reader = command.ExecuteReader();
 while (reader.Read())
 {
  Console.WriteLine("test id: " + reader.GetDecimal(0));
 }

 Console.Write("{0}Press any key to continue...", Environment.NewLine);
 Console.ReadKey();
}

PROCEDURE FIND_TESTS
(
 P_ID              IN        TEST.ID%Type,
 P_TITLE         IN        TEST.TITLE%Type,
 P_TYPE_CODE IN        TEST.TYPE_CODE%Type,
 P_CURSOR      OUT     CURSOR REF
)

AS

BEGIN

OPEN       
              P_CURSOR FOR
SELECT    
              ID, 
              TITLE,
              TYPE_CODE
FROM       
              TEST
WHERE     
              (P_ID IS NULL OR ID = P_ID)
              AND (P_TITLE IS NULL OR TITLE LIKE P_TITLE) 
              AND (P_TYPE_CODE IS NULL OR TYPE_CODE LIKE P_TYPE_CODE)
ORDER BY 
              ID ASC;
END;

A couple of examples how you can use this query:

using (OracleConnection conn = new OracleConnection("User Id=u;password=p;Data Source=ORCL"))
{
 conn.Open();

 OracleCommand command = conn.CreateCommand();
 command.CommandText = "TIMVW.MYPACKAGE.FIND_TESTS";
 command.CommandType = CommandType.StoredProcedure;

 // select all tests of type_code "book" that have a title that starts with "Myst"
 command.Parameters.Add("P_ID", OracleDbType.Int32, 10, DBNull.Value, ParameterDirection.Input);
 command.Parameters.Add("P_TITLE", OracleDbType.Varchar2, 20, "Myst%", ParameterDirection.Input);
 command.Parameters.Add("P_TYPE_CODE", OracleDbType.Varchar2, 20, "book", ParameterDirection.Input);
 command.Parameters.Add("P_CURSOR", OracleDbType.RefCursor, ParameterDirection.Output);

 // select the test with id 1
 //command.Parameters.Add("P_ID", OracleDbType.Int32, 10, 1, ParameterDirection.Input);
 //command.Parameters.Add("P_TITLE", OracleDbType.Varchar2, 20, DBNull.Value, ParameterDirection.Input);
 //command.Parameters.Add("P_TYPE_CODE", OracleDbType.Varchar2, 20, DBNull.Value, ParameterDirection.Input);
 //command.Parameters.Add("P_CURSOR", OracleDbType.RefCursor, ParameterDirection.Output);

 OracleDataReader reader = command.ExecuteReader();
 while (reader.Read())
 {
  Console.WriteLine("test id: " + reader.GetDecimal(0));
 }
 
 Console.Write("{0}Press any key to continue...", Environment.NewLine);
 Console.ReadKey();
}

DEFINE _EDITOR='gvim -c "set filetype=sql"'
SET SERVEROUTPUT ON
SET LINESIZE 120
SET AUTOCOMMIT OFF
ALTER SESSION SET NLS_DATE_FORMAT='YYYY-MM-DD';

In a stored procedure i created and filled an instance of NUMBER_TABLE (CREATE TYPE NUMBER_TABLE AS TABLE OF NUMBER) and my stored procedure tried to select all the rows in that table (SELECT * FROM V_NUMBER_TABLE). Apparently the engine didn’t know this type @runtime despite the fact that i declared it in my stored procedure (V_NUMBER TABLE NUMBER_TABLE := NUMBER_TABLE();) and the engine compiled the package without errors. I got round that problem as following:

SELECT * FROM (CAST(V_NUMBER_TABLE AS NUMBER_TABLE));

CREATE TABLE laptimes (
 lap_id SERIAL NOT NULL,
 player_id INT NOT NULL,
 laptime INT NOT NULL,
 PRIMARY KEY (lap_id)
);

INSERT INTO laptimes (player_id, laptime) VALUES (1, 250);
INSERT INTO laptimes (player_id, laptime) VALUES (1, 450);
INSERT INTO laptimes (player_id, laptime) VALUES (1, 350);
INSERT INTO laptimes (player_id, laptime) VALUES (1, 300);
INSERT INTO laptimes (player_id, laptime) VALUES (1, 327);

INSERT INTO laptimes (player_id, laptime) VALUES (2, 327);
INSERT INTO laptimes (player_id, laptime) VALUES (2, 249);
INSERT INTO laptimes (player_id, laptime) VALUES (2, 123);
INSERT INTO laptimes (player_id, laptime) VALUES (2, 489);
INSERT INTO laptimes (player_id, laptime) VALUES (2, 158);

INSERT INTO laptimes (player_id, laptime) VALUES (3, 158);
INSERT INTO laptimes (player_id, laptime) VALUES (3, 120);
INSERT INTO laptimes (player_id, laptime) VALUES (3, 190);

INSERT INTO laptimes (player_id, laptime) VALUES (4, 600);

Now imagine that you want to display the best 3 results for each player. Here’s how:

SELECT *
FROM laptimes AS l1
WHERE lap_id IN (
 SELECT lap_id
 FROM laptimes AS l2
 WHERE l1.player_id = l2.player_id
 ORDER BY laptime ASC
 LIMIT 3
)
ORDER BY player_id ASC, laptime ASC;

• newsitems(news_id,post_id)
• postitems(post_id,user_id,content)
• users(user_id,name,password)

We want to display for each newsitem the content and the author.

Our base table would be the newsitems, and then we join using the item_id. Thus the query would be:

SELECT *
FROM newsitems
INNER JOIN ON postitems USING (post_id)

This returns a “virtual table” that has looks like this result(news_id,post_id,user_id,content).

Now we still need to get the username, so we use our result table and perform a join on the users table. Thus the query would be:

SELECT *
FROM result
INNER JOIN users USING (user_id)

If we combine our first two queries, we end up with this:

SELECT *
FROM newsitems
INNER JOIN postitems USING (post_id)
INNER JOIN users USING (user_id)

Conclusion: Look at A*B*C as (A*B)*C to easily understand multiple joins

SELECT SUBSTRING_INDEX(body,' ',50) AS dn FROM mytable

SELECT *
FROM foo
ORDER BY FIELD(column, 'Z', 'B', 'C')