how to
select name,family from student where name="X"
without its column name.
for example :
select "column1","column2" from student where "column1"="x"
or for example
select "1","2" from student where "1"="x"
"1" is column1
"2" is column2
i dont want to say columns name. i want to say just its number or other....
idont tired from select *. but it just for that i dont know the columns name but i know where they are. my columns name are change every i want to read the file but its data are same, and the data are in the same columns in each file.
Although you can not use field positions specifiers in the SELECT statement, the SQL standard includes the INFORMATION_SCHEMA where the dictionary of your tables is defined. This includes the COLUMNS view where all the fields of all tables are defined. And in this view, there is a field called ORDINAL_POSITION which you can use to assist in this problem.
If you query
SELECT ORDINAL_POSITION, COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'TABLE'
ORDER BY ORDINAL_POSITION
then you can obtain the column names for the ordinal positions you want. From there you can prepare a SQL statement.
You could use temp table as:
DECLARE #TB TABLE(Column1 NVARCHAR(50),...)
INSERT #TB
SELECT * FROM student
Then use it:
SELECT Column1 FROM #TB WHERE Column1='aa'
If it's a string you can do this :
Select Column1 + '' From Table
If it's a number you can do this :
Select Column1 + 0 From Table
If it's a datetime you can do this :
Select dateadd(d, 0, Column1) From Table
And similarly for other data types..
No, you can not use the ordinal (numeric) position in the SELECT clause. Only in Order by you can.
however you can make your own column alias...
Select Column1 as [1] From Table
You can use alias:
SELECT name AS [1], family AS [2] FROM student WHERE name="X"
It's just not possible. Unfortunately, they didn't think about table-valued functions, for which information_schema is not available, so good luck with that.
Related
The results of my SQL query include null values. How do I filter out null values?
The syntax may vary depending on the database you are using but you can explicitly exclude nulls in the where clause. For example, the following will exclude null values in the primary_author field:
SELECT
date,
primary_author,
ISBN
FROM
books
WHERE
primary_author IS NOT NULL;
My example works on every database I know, so it should work for you =)
SELECT *
FROM TABLE_NAME
WHERE COLUMN_NAME IS NOT NULL
Here you can find a simple explanation and some examples: https://www.w3schools.com/sql/sql_null_values.asp
But some times you want to replace null values for a default value, like 'X', in this case, we should know the database for correct syntax, here some examples:
Oracle:
SELECT nvl(column_name,'X')
FROM TABLE_NAME
Sqlite:
SELECT ifnull(column_name,'X')
FROM TABLE_NAME
SqlServer:
SELECT coalesce(column_name,'X')
FROM TABLE_NAME
I found this (working) statement in some code I maintain:
SELECT 'TABLE_NAME' AS TEMP
FROM TABLE_NAME
WHERE ROWNUM = 1
and while I am familiar with the AS use for table columns, e.g.
USE mydatabase;
SELECT day_of_order AS "Date",
customer As "Client",
product,
quantity
FROM orders;
I couldn't find documentation for using the entire table's name as a column.
How does this work? and what would be the intended use of such statement?
It just looks like they're selecting a literal string of the table name, and put it in a column called TEMP. It will only return one row because of the WHERE ROWNUM = 1. They could have just as easily done:
SELECT 'TABLE_NAME' AS TEMP FROM DUAL
As for what you'd use it for... that's a good question. :)
What is the most efficient and elegant SQL query looking for a string containing the words "David", "Moses" and "Robi". Assume the table is named T and the column C.
Select * from table where
columnname like'%David%' and
columnname like '%Moses%' and columnname like'%Robi%'
In SQL Server 2005+ with Full-Text indexing switched on, I'd do the following:
SELECT *
FROM T
WHERE CONTAINS(C, '"David" OR "Robi" OR "Moses"');
If you wanted your search to bring back results where the result is prefixed with David, Robi or Moses you could do:
SELECT *
FROM T
WHERE CONTAINS(C, '"David*" OR "Robi*" OR "Moses*"');
Here is what I uses to search for multiple words in multiple columns - SQL server
Hope my answer help someone :) Thanks
declare #searchTrm varchar(MAX)='one two three ddd 20 30 comment';
--select value from STRING_SPLIT(#searchTrm, ' ') where trim(value)<>''
select * from Bols
WHERE EXISTS (SELECT value
FROM STRING_SPLIT(#searchTrm, ' ')
WHERE
trim(value)<>''
and(
BolNumber like '%'+ value+'%'
or UserComment like '%'+ value+'%'
or RequesterId like '%'+ value+'%' )
)
If you care about the sequence of the terms, you may consider using a syntax like
select * from T where C like'%David%Moses%Robi%'
Oracle SQL :
select *
from MY_TABLE
where REGEXP_LIKE (company , 'Microsodt industry | goglge auto car | oracles database')
company - is the database column name.
results - this SQL will show you if company column rows contain one of those companies (OR phrase)
please note that : no wild characters are needed, it's built in.
more info at : http://www.techonthenet.com/oracle/regexp_like.php
if you put all the searched words in a temporaray table say #tmp and column col1, then you could try this:
Select * from T where C like (Select '%'+col1+'%' from #temp);
Maybe EXISTS can help.
and exists (select 1 from #DocumentNames where pcd.Name like DocName+'%' or CD.DocumentName like DocName+'%')
Oracle SQL:
There is the "IN" Operator in Oracle SQL which can be used for that:
select
namet.customerfirstname, addrt.city, addrt.postalcode
from schemax.nametable namet
join schemax.addresstable addrt on addrt.adtid = namet.natadtid
where namet.customerfirstname in ('David', 'Moses', 'Robi');
I need to select rows where a field begins with one of several different prefixes:
select * from table
where field like 'ab%'
or field like 'cd%'
or field like "ef%"
or...
What is the best way to do this using SQL in Oracle or SQL Server? I'm looking for something like the following statements (which are incorrect):
select * from table where field like in ('ab%', 'cd%', 'ef%', ...)
or
select * from table where field like in (select foo from bar)
EDIT:
I would like to see how this is done with either giving all the prefixes in one SELECT statement, of having all the prefixes stored in a helper table.
Length of the prefixes is not fixed.
Joining your prefix table with your actual table would work in both SQL Server & Oracle.
DECLARE #Table TABLE (field VARCHAR(32))
DECLARE #Prefixes TABLE (prefix VARCHAR(32))
INSERT INTO #Table VALUES ('ABC')
INSERT INTO #Table VALUES ('DEF')
INSERT INTO #Table VALUES ('ABDEF')
INSERT INTO #Table VALUES ('DEFAB')
INSERT INTO #Table VALUES ('EFABD')
INSERT INTO #Prefixes VALUES ('AB%')
INSERT INTO #Prefixes VALUES ('DE%')
SELECT t.*
FROM #Table t
INNER JOIN #Prefixes pf ON t.field LIKE pf.prefix
you can try regular expression
SELECT * from table where REGEXP_LIKE ( field, '^(ab|cd|ef)' );
If your prefix is always two characters, could you not just use the SUBSTRING() function to get the first two characters of "field", and then see if it's in the list of prefixes?
select * from table
where SUBSTRING(field, 1, 2) IN (prefix1, prefix2, prefix3...)
That would be "best" in terms of simplicity, if not performance. Performance-wise, you could create an indexed virtual column that generates your prefix from "field", and then use the virtual column in your predicate.
Depending on the size of the dataset, the REGEXP solution may or may not be the right answer. If you're trying to get a small slice of a big dataset,
select * from table
where field like 'ab%'
or field like 'cd%'
or field like "ef%"
or...
may be rewritten behind the scenes as
select * from table
where field like 'ab%'
union all
select * from table
where field like 'cd%'
union all
select * from table
where field like 'ef%'
Doing three index scans instead of a full scan.
If you know you're only going after the first two characters, creating a function-based index could be a good solution as well. If you really really need to optimize this, use a global temporary table to store the values of interest, and perform a semi-join between them:
select * from data_table
where transform(field) in (select pre_transformed_field
from my_where_clause_table);
You can also try like this, here tmp is temporary table that is populated by the required prefixes. Its a simple way, and does the job.
select * from emp join
(select 'ab%' as Prefix
union
select 'cd%' as Prefix
union
select 'ef%' as Prefix) tmp
on emp.Name like tmp.Prefix
How do I select all records that contain "LCS" within the title column in sql.
SELECT * FROM TABLE WHERE TABLE.TITLE LIKE '%LCS%';
% is the wild card matcher.
Look into the LIKE clause
Are you looking for all the tables with a column name which contains the LCS in them? If yes the do this
select table_name
from information_schema.columns
where column_name like '%lcs%'