How does wildcards works in sql. If I do select * from table it give all the fields. But if I do select a* from table it gives error. Shouldn't it give all fields which begins with a?
I am little confused.
SELECT * FROM tableName literally means "select all columns from tableName".
Philip Graham is right about his answer where he asked to use a.*
Wildcards help you search for strings about which you are not sure. These are almost always used with the LIKE keyword and put in WHERE clauses or searched CASE statements.
There are two wildcard characters - % and _.
% is used to find any string of 0 or more length.
E.g.,
SELECT firstName
FROM persons
WHERE UPPER(firstName) LIKE 'J%'
This will return all the firstName from the persons table where firstname starts with letter J. This would return "Jason", "James", "Josh", "Jessica" and much more.
Note that UPPER function was used to eliminate case sensitivity.
Next, you can have an _ character that looks for the presence of one single character.
SELECT firstName
FROM persons
WHERE UPPER(firstName) LIKE 'J_M__'
This would return "James", "Jimmy", "Jamos", "Jxmx" and filter away any "Jason", "Jaguar", etc.
For more info click here
You can use a.* where a is the name of the table. For instance in
select a.* from a left join b on a.id = b.id
You would return only the fields from a but not from b
If want to use a wild card in SQL, You need to key on the column that you want to filter using LIKE.
SELECT *
FROM table
WHERE column_name LIKE 'a%';
This will give you everything that begins with 'a' on that column.
If you don't want all the columns, you must explicitly give the name of each column that you want in the query.
SELECT LastName, FirstName, Address
FROM table
So if you want all the fields that begin with 'a' you must name all the fields that begin with 'a' in the SELECT statement.
Hope this helps.
Related
Following is the query to select column data from table, where column data starts with a OR b OR c. But the answer i am looking for is to Select data which starts with List of Strings.
SELECT * FROM Table WHERE Name LIKE '[abc]%'
But i want something like
SELECT * FROM Table WHERE Name LIKE '[ab,ac,ad,ae]%'
Can anybody suggest what is the best way of selecting column data which starts with list of String, I don't want to use OR operator, List of strings specifically.
The most general solution you would have to use is this:
SELECT *
FROM Table
WHERE Name LIKE 'ab%' OR Name LIKE 'ac%' OR Name LIKE 'ad%' OR Name LIKE 'ae%';
However, certain databases offer some regex support which you might be able to use. For example, in SQL Server you could write:
SELECT *
FROM Table
WHERE NAME LIKE 'a[bcde]%';
MySQL has a REGEXP operator which supports regex LIKE operations, and you could write:
SELECT *
FROM Table
WHERE NAME REGEXP '^a[bcde]';
Oracle and Postgres also have regex like support.
To add to Tim's answer, another approach could be to join your table with a sub-query of those values:
SELECT *
FROM mytable t
JOIN (SELECT 'ab' AS value
UNION ALL
SELECT 'ac'
UNION ALL
SELECT 'ad'
UNION ALL
SELECT 'ae') v ON t.vame LIKE v.value || '%'
I'm using an Oracle database and I want to know how can I find rows in a varchar type column where the values of that column has a string which contains some character.
I'm trying something like this (that's a simple example of what I want), but it doesn't work:
select p.name
from person p
where p.name contains the character 'A';
I also want to know if I can use a function like chr(1234) where 1234 is an ASCII code instead of the 'A' character in my example query, because in my case I want to search in my database values where the name of a person contains the character with 8211 as ASCII code.
With the query select CHR(8211) from dual; I get the special character that I want.
Example:
select p.name
from person p
where p.name contains the character chr(8211);
By lines I assume you mean rows in the table person. What you're looking for is:
select p.name
from person p
where p.name LIKE '%A%'; --contains the character 'A'
The above is case sensitive. For a case insensitive search, you can do:
select p.name
from person p
where UPPER(p.name) LIKE '%A%'; --contains the character 'A' or 'a'
For the special character, you can do:
select p.name
from person p
where p.name LIKE '%'||chr(8211)||'%'; --contains the character chr(8211)
The LIKE operator matches a pattern. The syntax of this command is described in detail in the Oracle documentation. You will mostly use the % sign as it means match zero or more characters.
The answer of ADTC works fine, but I've find another solution, so I post it here if someone wants something different.
I think ADTC's solution is better, but mine's also works.
Here is the other solution I found
select p.name
from person p
where instr(p.name,chr(8211)) > 0; --contains the character chr(8211)
--at least 1 time
Thank you.
You used the keyword CONTAINS in your sample queries and question. CONTAINS lets you search against columns that have been indexed with an Oracle*Text full-text index.
Because these columns are full-text indexed, you can efficiently query them to search for words and phrases anywhere with the text columns without triggering a full table scan. Depending upon their usage, using LIKE or INSTR will almost always result in a full table scan.
CONTAINS is used to search for words and phrases. Although there are many options it is not appropriate if you are looking for embedded characters such as 'A' or chr(8211).
The following query will return all rows that contain the word "smith" anywhere in their text.
SELECT score(1), p.name
FROM person p
WHERE CONTAINS(p.name, 'smith', 1) > 0;
For more details see:
How does contains() in PL-SQL work?
Oracle SQL "contains" clause tips
Oracle: Contains Documentation
Oracle: Contains Operators
Just in case you need you need to find if a column has any values that have character in it, you can use regexp_like. The first parameter is the column name to be checked and the second parameter is the regular expression.
If the below sql returns count greater than zero, that means there are some row(s) in which there is 1 or more character in it.
SELECT COUNT(*)
FROM TABLE_NAME
WHERE regexp_like (COLUMN_NAME, '[^0-9]')
I want to get List of students from a particular section and with other search criteria. I am doing this:-
declare #sectionId int, #name varchar
select #sectionId=23
select #name='a'
select UserId, FirstName from StudentMaster
Where FirstName Like #name and UserId IN
(
select UserId from StudentMaster
Intersect
select StudentId from StudentInSections where SectionId=#sectionId
)
but it is not giving right answer. If I only write Userid condition it works properly but I have to get list with whole search criteria.
is there anybody to help me?
The problem is the LIKE operand. If #name is 'a' this will only return students whose name is 'a' or 'A'. If you want student names starting with "a" you must add a wildcard "%"
FirstName LIKE 'a%'
(Some SQL dialects like MS Access use the wildcard "*" instead of "%".)
Note on case sensitive/insensitive search. Depending on the SQL dialect and the collation used for the column the search will be case sensitive or not. If you do not want to make a case sensitive search (i.e. you want to find students whose name starts with "a" or "A"), you can do this:
UPPER(FirstName) LIKE 'A%'
Or on the SQL-Server
FirstName COLLATE UTF8_GENERAL_CI LIKE '%a'
Where CI means case insensitive.
select sm.UserId, sm.FirstName from StudentMaster sm
inner join StudentInSections ss on ss.StudentId = sm.UserId
Where sm.FirstName Like #name
and ss.SectionId = #sectionId
Something like that should work. You just need to learn how to use inner joins.
I'm using the Firefox sqlite manager addon and I have a database table named - drinktable. I need to extract all the columns where the title matches a certain string. This is the query I am running right now -
SELECT * FROM drinktable where title = 'First Drink';
But it won't return anything. It just shows the 4 columns in the database, but nothing in those columns. Can someone please tell me why ?
I have a database table named - drinktable.
One thing in your question. Your table name is drinktable and you are querying against first, is it a typo. In SQL Select statement you specify table name after from and column name in where clause
SELECT * FROM drinktable where first = 'First Drink';
Select * from <TableName> where <ColumnName> = 'Value to compare';
If your table name is first and column name is drinktable then chances are that there are now row(s) with column drinktable set to 'First Drink'. You might have spaces or some other characters. Try
SELECT * FROM first where drinktable like '%First Drink%';
EDIT:
Based on your edited question, chances are you have spaces or some other characters, try:
SELECT * FROM drinktable where title like '%First Drink%';
I'm trying to make a search feature that will search multiple columns to find a keyword based match. This query:
SELECT title FROM pages LIKE %$query%;
works only for searching one column, I noticed separating column names with commas results in an error. So is it possible to search multiple columns in mysql?
If it is just for searching then you may be able to use CONCATENATE_WS.
This would allow wild card searching.
There may be performance issues depending on the size of the table.
SELECT *
FROM pages
WHERE CONCAT_WS('', column1, column2, column3) LIKE '%keyword%'
You can use the AND or OR operators, depending on what you want the search to return.
SELECT title FROM pages WHERE my_col LIKE %$param1% AND another_col LIKE %$param2%;
Both clauses have to match for a record to be returned. Alternatively:
SELECT title FROM pages WHERE my_col LIKE %$param1% OR another_col LIKE %$param2%;
If either clause matches then the record will be returned.
For more about what you can do with MySQL SELECT queries, try the documentation.
If your table is MyISAM:
SELECT *
FROM pages
WHERE MATCH(title, content) AGAINST ('keyword' IN BOOLEAN MODE)
This will be much faster if you create a FULLTEXT index on your columns:
CREATE FULLTEXT INDEX fx_pages_title_content ON pages (title, content)
, but will work even without the index.
1)
select *
from employee em
where CONCAT(em.firstname, ' ', em.lastname) like '%parth pa%';
2)
select *
from employee em
where CONCAT_ws('-', em.firstname, em.lastname) like '%parth-pa%';
First is usefull when we have data like : 'firstname lastname'.
e.g
parth patel
parth p
patel parth
Second is usefull when we have data like : 'firstname-lastname'. In it you can also use special characters.
e.g
parth-patel
parth_p
patel#parth
Here is a query which you can use to search for anything in from your database as a search result ,
SELECT * FROM tbl_customer
WHERE CustomerName LIKE '%".$search."%'
OR Address LIKE '%".$search."%'
OR City LIKE '%".$search."%'
OR PostalCode LIKE '%".$search."%'
OR Country LIKE '%".$search."%'
Using this code will help you search in for multiple columns easily
SELECT * FROM persons WHERE (`LastName` LIKE 'r%') OR (`FirstName` LIKE 'a%');
Please try with above query.