I need to create am index in SQL however it needs to display the records by entering only a part of the name. The index should be created to retrieve the student information using part of the student name (i.e. if the name if Johnanesburg; the user can input John)
I used the syntax below but it wont work
create index Student ON Student(SName)
SELECT * FROM Student WHERE StRegNo LIKE A%
go
I think your problem is here: A%
Try wrapping it in apostrophes.
SELECT *
FROM Student
WHERE StRegNo LIKE 'A%'
Also, you may want a GO statement after you create your index.
The index you are creating over SName will not provide as much benefit for the select statement you are running as one created over StRegNo. Assuming that StRegNo is the primary key on the Student table you could try:
CREATE CLUSTERED INDEX IX_Student on Student(StRegNo)
SELECT *
FROM Student
WHERE StRegNo LIKE 'A%'
However it appears that the SQL you have provided is at odds with your question. If you want to search based on student name then you might want the following instead.
CREATE NONCLUSTERED INDEX IX_Student on Student(SName)
SELECT *
FROM Student
WHERE SName LIKE 'A%'
Ardman got it right regarding your query %A => '%A'. Now as for the index, that's another story that no index can help you with at the time, neither can full text search. If you want to look for names starting with #A (i.e. John%), an ordered index could help but otherwise (i.e. %bur%), you will go for a full table scan !
Related
I have a row in a table that contains "DS012345" in a column called description
When I use this query:
Select * from Tablename where Contains(Description, ' "*012345*" ')
This query returns no result.
I have created the unique index, fulltext catalog, I have turned off the Stop Words using the Object Explorer. Still do not know why it does not return that row.
Any suggestion or cause for this?
Thanksl.
Why not just use LIKE instead to do a search.
Select * from Tablename where Description LIKE '%012345%'
Just does a search where 012345 appears anywhere within the description column.
Stop words is the number that it starts to seek for a word in your database..
Fulltext should be used to get the exact word, if you just want a part of the word you should use LIKE %...%.
Hello I currently have 2 tables like this:
Parcel which has idParcel,quantityParcel,idProduct
and
Product which has idProduct, nameProduct
When I try to execute Aggr( sum(quantityParcel),[idProduct] ) it works just fine making the sum of quantityParcel by idProduct but when I try to run Aggr( sum(quantityParcel),[nameProduct] ) it just returns the sum of all quantityParcel values without grouping anything, is there any way I can group by nameProduct referencing it from the Product table? The reason I want to do this is because I want to show the actual product name in my dimension instead of just the idProduct number, thanks :)
If you use nameProduct as Dimension why don't just use: sum(quantityParcel)
another option is to use NODISTINCT : Aggr(NODISTINCT sum(quantityParcel),[nameProduct] )
I am very new at PostgreSQL and want to be able to delete rows from a table if a specific column starts with a certain pattern.
For example,
I have a reference column which is a sort of time stamp (YYMMDDHHMM). If the reference column starts with 16********, then i'd like it to be deleted.
So far, I know how to delete the column if the whole reference is known. E.g:
DELETE FROM my_tbl WHERE name='test1' AND ref_no=1601010000;
However, I need to change this so that the condition only specifies the first 2 digits of the reference number.
Read about LIKE operator: https://www.postgresql.org/docs/8.3/static/functions-matching.html
Use this command to delete rows:
DELETE FROM my_tbl WHERE reference LIKE '16%'
Before deleting rows from the table, first check if a delete condition really works as expected using it in a regular SELECT statement:
SELECT * FROM my_tbl WHERE reference LIKE '16%'
If reference column is not of type varchar but for example int, you need first to conver (cast) it to a varchar datatype in this way:
SELECT * FROM my_tbl WHERE reference::varchar LIKE '16%'
DELETE FROM my_tbl WHERE reference::varchar LIKE '16%'
Try the 'like' operator, it allows you to do pattern matching.
DELETE FROM my_tbl WHERE name LIKE '%test%';
The '%' character is a wildcard. The above line should delete every column where the name contains the string 'test'.
More info here: pattern matching
In SQL Server, i am inserting multiple records into table using batch update. How do i get back the ID's (unique primary key) which is being created after batch update?
If I insert one record, I can get the last inserted using IDENT(tableName). I am not sure how to get if I do batch update. Please help.
For example, I have student table, with ROLE NO and NAME. ROLE NO is auto incremented by 1, as soon I insert the names into DB using java program. I will add 3 rows at a time using batch update from my java code. In DB, it gets added with ROLE NO 2, 3 and 4. How do I get these newly generated ID in my java program, please help
I tried getting ids using getgeneratedkeys method after I do executebatch. I get exception. Is batch update + get generated keys supported.?
In SQL Server when you do an insert there is an extra option your query; OUTPUT. This will let you capture back the data you inserted into the table - including your id's. You have to insert them into a temporary table; so something like this (with your table/ column names will get you there.
declare #MyNewRoles Table (Name, RoleNo)
insert into tblMyTable
(Name)
Select
Name
Output
inserted.Name, Inserted.RoleNo
into #MyNewRoles
From tblMyTableOfNames
select * from #MyNewRoles
If you don't mind adding a field to your table, you could generate a unique ID for each batch transaction (for example, a random UUID), and store that in the table as well. Then, to find the IDs associated with a given transaction you would just need something like
select my_id from my_table where batch_id = ?
Which one of the following queries is faster (LIKE vs CONTAINS)?
SELECT * FROM table WHERE Column LIKE '%test%';
or
SELECT * FROM table WHERE Contains(Column, "test");
The second (assuming you means CONTAINS, and actually put it in a valid query) should be faster, because it can use some form of index (in this case, a full text index). Of course, this form of query is only available if the column is in a full text index. If it isn't, then only the first form is available.
The first query, using LIKE, will be unable to use an index, since it starts with a wildcard, so will always require a full table scan.
The CONTAINS query should be:
SELECT * FROM table WHERE CONTAINS(Column, 'test');
Having run both queries on a SQL Server 2012 instance, I can confirm the first query was fastest in my case.
The query with the LIKE keyword showed a clustered index scan.
The CONTAINS also had a clustered index scan with additional operators for the full text match and a merge join.
I think that CONTAINS took longer and used Merge because you had a dash("-") in your query adventure-works.com.
The dash is a break word so the CONTAINS searched the full-text index for adventure and than it searched for works.com and merged the results.
Also try changing from this:
SELECT * FROM table WHERE Contains(Column, "test") > 0;
To this:
SELECT * FROM table WHERE Contains(Column, '"*test*"') > 0;
The former will find records with values like "this is a test" and "a test-case is the plan".
The latter will also find records with values like "i am testing this" and "this is the greatest".
I didn't understand actually what is going on with "Contains" keyword. I set a full text index on a column. I run some queries on the table.
Like returns 450.518 rows but contains not and like's result is correct
SELECT COL FROM TBL WHERE COL LIKE '%41%' --450.518 rows
SELECT COL FROM TBL WHERE CONTAINS(COL,N'41') ---40 rows
SELECT COL FROM TBL WHERE CONTAINS(COL,N'"*41*"') -- 220.364 rows