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I have a two table first is simple primary key based table and second table is keyvaluepair for maintaining records.
Now I want to get records from Table in a single object. If they come as comma separate it's good.
Suppose I have table
ID valueID.
When I will run select query I not want a list of rows. I want a single column (in a row) that I can get the information about all valueIds.
Could someone explain me how can I get them in one instead of list?
You probably want to use GROUP_CONCAT.
SELECT GROUP_CONCAT(valueID) FROM table
http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat
If you need both the ID and the valueID, you're better off sticking with an array.
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I am trying to join an old sql table with a new one but exclude the duplicate entries, this needs to be in a delphi program as well, and im a noob at that, any ideas?
These both keywords will make your data to combine and display in a single column.
Union - Removes the duplicate entries of the table
Union All - Includes the duplicate entries
It would be better if you provide an example with input and output, that would clarify your question the most.
you can use the union all operator instead of the union operator for joining two tables that not remove duplicates from the table.
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Using MySQL, I want to retrieve all rows from a table A where a field contains "EQ" for example, copy them into table B (which has exactly the same field), and then delete them from table A.
I heard about triggers. Is that the right approach?
You need 2 SQL statements. First for inserting the data rows from A to B, and then for deleting those rows from A.
INSERT INTO B
SELECT *
FROM A
WHERE Field LIKE '%EQ%';
DELETE
FROM A
WHERE Field LIKE '%EQ%';
Triggers are a way to automate some activities when some other activity in a separate table happens. If you need to make sure that the above 2 operations should be triggered as soon someone INSERTS/DELETES/UPDATES on some other table, then you can create a trigger for that purpose. But with the simple requirement you gave above without any such dependency, I do not see a need of a trigger here.
If you do have such dependency and need, you have to provide proper requirements with details here.
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if I had a mysql table that has, lets say 300 million rows, how would I search for a row using
SELECT id WHERE coloumn = "abc" ;
most efficiently? Can I prepare the data so it would help the sql searching through the data? Or does it parse the rows row by row?
The SQL 101 answer here is an index using CREATE INDEX:
CREATE INDEX column_index ON table_name (`column_name`)
This of course depends on your schema. You can index more than one column as well and can apply UNIQUE constraints to ensure that each value is used only once.
On large tables the CREATE INDEX operation will be brutally slow to create the first time, so schedule some downtime if necessary. Once created it will be kept up-to-date automatically.
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I have a table named 'tweet' and its column 'text'. The column contains a sentence (many words) in each record. Then I wanna search the most word from the column. Is that possible to do that in MySQL query? If so, then I want to know also to add exception words like: 'a', 'I', etc...
I thought it's similar with this post
But it's using PHP.
I very appreciate for any help!
SQL is not the obvious tool for something like this. But, if you are going to use SQL, I would suggest that you parse the text into a TweetWords table, with one row per "tweet" and word in the tweet (along with position information).
If you are inserting the data through PHP, you can do the parsing there and then insert each word independently.
Then the count is easy, using a basic aggregation query.
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I have a table named 'User' and it has an autoincremented field userID.
I want to retrieve that userID in my servlet. There is no such parameter/field referred to on that respective HTML. How can I use that userID in my servlet?
I would say your question is far to broad for a definite answer mate but here goes my best guess.
I assume you run this table and data in mysql since you tagged this as mysql.
you can retrieve the data you wish with the query as below:
SELECT userID FROM User;
Note: If you have more than 1 this will return all of them. If you want to limit this down to 1 you will need to match that to another unique parameter in your table. For example lets say you have a column in User table called "telephone"
the query would be:
SELECT userID FROM User WHERE telephone = '1234567890';
You can then display the result in your html, depending on what language you use to execute this query with.
Hope this helps