Is there a way to show row values as column values.
Lets say I have a table called A and which contains 5 records with 3 columns. Below image show the data set. Rows always 5.
In Here I need to show value column values in a line with temporary column names
If I use simple select query as
Select row1.value as col1, row2.value as col2, row3.value as col3, row4.value as col4, row5.value as col5
so my expected result need to show as below
Please tell me how to use select query to get this result in MySQL
Related
I need to create an identical copy of many records in a table. The table has a PK id, which of course will be different, in the freshly-copied records.
For example, let's say i have a scrum_card table, with the following non-unique columns: name, description, board_id
I have a dynamic array of id's of records, which i wish to duplicate: [34,56,32,3445,...]
How do i tell MYSQL, to fetch the data from all those records, and make a batch-insert of those same records?
In "human" syntax it would look something like this: "Select all columns(besides id) from scrum_card where the id's are [array of id's], then duplicate each found record".
Use INSERT INTO ... SELECT... and in the list of columns do not include the id:
insert into scrum_card(name, description, board_id)
select name, description, board_id
from scrum_card
where id in (34,56,32,3445,...)
You can use INSERT using a SELECT result set as the source, instead of a set of literal row tuples with VALUES(...).
INSERT INTO new_table (id, col1, col2, col3...)
SELECT NULL, col1, col2, col3...
FROM old_table
WHERE id IN (34,56,32,3445,...)
Using NULL in place of the id column in the SELECT will return NULL for each row, which will cause new_table to generate a new id value.
But SQL does not have any way to do a wildcard like "all columns except id," besides you typing the column names in.
I have a database table. That table has 4 columns. In 3 columns members(values) want to access the 4th column value.
So here i don't want to write same query for every member. I want to write only single query. So is it possible with single query? If possible how I can know which column has given those result set?
select 4thcolumn from tablename where lstcolumn=?1 or 2ndcolumn=?2 or 3rdcolumn=?3;
Using OR is a solution (but that requires you to repeat the parameter three times):
SELECT col4 FROM mytable col1 =:myvalue OR col2 =:myvalue OR col3 = :myvalue;
One solution to shorten the query (and pass a unique parameter) is to use IN:
SELECT col4 FROM mytable WHERE :myvalue IN (col1, col2, col3)
If you want to know which column matched, then this gets longer. In MySQL you can do:
SELECT
col4,
col1 = :myvalue is_col1,
col2 = :myvalue is_col2,
col3 = :myvalue is_col3
FROM mytable
WHERE :myvalue IN (col1, col2, col3)
This adds three columns in the result set: is_col1, is_col2, is_col3; the column(s) that matched will have value 1, other(s) will show 0.
i got 2 tables that i want to combine its data.
the id is my key field (incremental and distinct).
table 1 and table 2 field description for example:
id - name - value
i want to insert all of table 2 data into table 1, they have different data but in some rows the same id.
so when i try to:
INSERT INTO ladatabase.table2 SELECT * from ladatabase.table1;
i get duplicate entry error.
please help me to suggest how can i solve it and combine the data with different id values for the new data.
Alex.
here are 2 ways:
first you can use if the id AUTO INCREMENT
INSERT INTO ladatabase.table2
SELECT '', name, value from ladatabase.table1;
or you find the first free ID and add it
INSERT INTO ladatabase.table2
SELECT id+555 , name, value from ladatabase.table1;
No insert all fields (exclude 'id'-field from SELECT):
INSERT INTO ladatabase.table2 SELECT name,value from ladatabase.table1;
You need to copy all but the ID column, and it will assign new IDs. You need to list all the other columns explicitly. Leaving out the ID column will cause it to get its default value, which are sequential IDs for an auto_increment field.
INSERT INTO table2 (col2, col3, col4, ...)
SELECT col2, col3, col4, ...
FROM table1
I am working on redesigning of a legacy db and I have set new names to columns of old db. So, for instance, if olddb.oldtable under dbold has column descr, I have set it as description in new newdb.netable for column.
How can I mention individual columns in my query?
I am using MYSQL
Update: Both Databases are on different IP Addresses and I am using Navicat to transfer data.
You can try like this:
INSERT INTO newtable (col1, col2, ..., )
SELECT col1, col2, ..., FROM oldtable
By trying the above query you can insert the specific column. So for example if your newtable has a column as description and old table as descr then you can mention it like:
INSERT INTO newtable (col1, col2, `description`, ..., )
SELECT col1, col2, `descr` ,..., FROM oldtable
Also if the table column list is large and you want to copy all the columns and its data then you can simply use the wildcard charater * as:
INSERT INTO newtable
SELECT * FROM oldtable;
You can insert all columns at once without the need to mention the names using this:
INSERT INTO newtable (SELECT * FROM oldtable);
It will make an 1x1 match independently of column names.
If types don't match then will insert default values (not checked for all the type combination).
Note that column number must be the same on both tables otherwise an error like this will occur:
#1136 - Column count doesn't match value count at row 1
I am running some SQL queries from command line as follows:
cat my_query.sql | mysql --defaults-file=my_conf.cnf
I need to print column names whether the query returns any data or not.
Currently when there is no data to return, i.e when query returns an empty result set this command does not print anything.
For example my query is:
-- id=-1 doesn't exist
SELECT col1, col2 FROM table WHERE id=-1
I need this query to return
col1 col2
Instead it returns nothing.
Is it possible to do that using purely mysql and standard unix commands?
Thanks.
Adding a UNION ALL to a SELECT with "dummy"/blank data might work:
SELECT col1, col2 FROM table WHERE id=-1
UNION ALL
SELECT '', '' -- OR 0, 0 whatever is appropriate
;
I don't run queries from the command line, so this is assuming it normally would give you the column names if you had at least one row in the results.