I have one column called 'speeding' in a table containing many other columns. This column contains an integer that is foreign key to an entry on a table named Speeding. This table has columns 1-25 and an id that is referenced by the 'speeding' column from the first table.
Besides using join, is there any setting I can set on 'speeding' to make it automatically pull the associated data from the table Speeding?
You could create a view, a view is basically a SQL statement that is stored on the MySQL server and acts like a table
CREATE VIEW ViewName AS
SELECT tbl1.data, tbl2.speeding
FROM tbl1
INNER JOIN tbl2 ON tbl2.key = tbl1.key;
http://dev.mysql.com/doc/refman/5.0/en/create-view.html
You then use the view as you would use any table
SELECT data, speeding
FROM ViewName
Related
I have a table with a set column that contains 2 languages and another column on this table containing an order.
Is it possible migrate my table and to create a record in a new table for each set item with a MySQL query?
Directly migrating records works with records that have a set column without a language combination. But if a record would contain a set of languages I am left with one record with an empty column for language. I would preferably want 2 new records inserted into my fresh table.
One for each language in the set.
INSERT INTO newtable (
newtable.oldtable_id,
newtable.language,
newtable.order
)
SELECT oldtable.id, oldtable.languages, oldtable.order
FROM oldtable
WHERE oldtable.order IS NOT NULL;
I doubt it is possible but I would still like to know if somebody might have a workaround for this since I need to migrate the data somehow.
Create a helper table with one field that lists all languages that can be in the set column. The table can be a temporary one that you drop after the migration. Then create an insert ... select ... statement in which you join the source table on the helper table using MySQL's find_in_set() function:
INSERT INTO newtable (
newtable.oldtable_id,
newtable.language,
newtable.order
)
SELECT oldtable.id, helpertable.language, oldtable.order
FROM oldtable inner join helpertable ON find_in_set(helpertable.language, oldtable.languages)>0;
I have three tables-
Class (parent table)
Announcement (child table)
Class-ann(junction table)
All have their respective autoincrement ids
I am.looking to insert a new announcement into announcement table and assign it to a class in class-ann table
Please help me in that.
I can easily retrieve table using join. Should i use a join and then insert? Also classID will be predefined
I don't see any reason to use a join unless you're going to be using that data somewhere else. Just do an insert into the Class-ann table using the class_id and announcement_id from your other tables.
I have 2 tables that I am working with that use the same column; one table contains the text and the other table contains the images; they use the column listing_id so that the right text shows up with the right images;
my problem is that because column listing_id is auto-increment, my first table is able to have an insert into query that is able to insert the text and then +1 the column listing_id; however the 2nd table I use another INSERT INTO query will not have the right listing_id,
because some entries for listing_id have been deleted, meaning that the 2nd table's listing_id will always be behind the 1st tables listing_id;
how do I reference the column listing_id?
You need to create an INT column called something like "parent_id" in the dependant tables that stores the id of the main table that it is referencing. When you select records from the first, you would then JOIN the tables with the auto_increment field of the first field against the "parent_id" of the second.
As MrSlayer mentions, use the newly inserted ID of the first table to update "parent_id". You should typically have a unique ID field in the second table for uniqueness, but it shouldn't be part of the relationship to the first table.
If you're unclear about how to get the id that the first table auto_increments to when you insert, use mysql_insert_id().
mysql_query("INSERT INTO table1 ...");
echo "Last inserted record_id in table1 was " . mysql_insert_id();
INSERT INTO table1 (mytextcolumn) VALUES('text');
INSERT INTO table2 (parent_id,image_name) VALUES(LAST_INSERT_ID(),'someimage.png');
If I have two tables in a MySQL database that both have a column called order_number, given an order_number value but not knowing which table it comes from how would I go about setting up a query that would return the name of the table it was found in?
I am particularly interested in the name of the table so I can set up subsequent updates to that table.
Also, I am using PHP for the handling of the query.
select "tableA" as tableName,order_number from tableA where order_number=5
UNION
select "tableB" as tableName,order_number from tableB where order_number=5;
How to duplicate a table with keys & other structure features retained? including primary key, foreign keys, and indexes.
Can this be done with a single MySQL query?
I'm using "create table newtable as select..." but this method makes all keys & indexes lost.
duplicating a table from another table (with indexing and structure)cannot be done with a single query
you will need need 2 queries.
1) To create Duplicate table.
CREATE TABLE Table2 LIKE Table1;
This will create an exact copy of the table.
2) Fill in the Duplicate table with values from original table.
INSERT INTO Table2 SELECT * from Table1;
will fill Table2 with all the records fom Table1
you can do it in this query
CREATE TABLE a LIKE b
after you can insert
INSERT INTO a SELECT * FROM b
read more information in this article
Following query creates and duplicates data.
CREATE TABLE table2 SELECT * FROM table1