If I have table contents that looks like this :
id | value
------------
1 |CT 6510
2 |IR 52
3 |IRAB
4 |IR AB
5 |IR52
I need to get only those rows with contents starting with "IR" and then a number, (the spaces ignored). It means I should get the values :
2 |IR 52
5 |IR52
because it starts with "IR" and the next non space character is an integer. unlike IRAB, that also starts with "IR" but "A" is the next character. I've only been able to query all starting with IR. But other IR's are also appearing.
select * from public.record where value ilike 'ir%'
How do I do this? Thanks.
You can use the operator ~, which performs a regular expression matching.
e.g:
SELECT * from public.record where value ~ '^IR ?\d';
Add a asterisk to perform a case insensitive matching.
SELECT * from public.record where value ~* '^ir ?\d';
The symbols mean:
^: begin of the string
?: the character before (here a white space) is optional
\d: all digits, equivalent to [0-9]
See for more info: Regular Expression Match Operators
See also this question, very informative: difference-between-like-and-in-postgres
Related
I have an nvarchar(50) column myCol with values like these 16-digit, alphanumeric values, starting with '0':
0b00d60b8d6cfb19, 0b00d60b8d6cfb05, 0b00d60b8d57a2b9
I am trying to delete rows with myCol values that don't match those 3 criteria.
By following this article, I was able to select the records starting with '0'. However, despite the [a-z0-9] part of the regex, it also keeps selecting myCol values containing special characters like 00-d#!b8-d6/f&#b. Below is my select query:
SELECT * from Table
WHERE myCol LIKE '[0][a-z0-9]%' AND LEN(myCol) = 16
How should the expression be changed to select only rows with myCol values that don't contain special characters?
If the value must only contain a-z and digits, and must start with a 0 you could use the following:
SELECT *
FROM (VALUES(N'0b00d60b8d6cfb19'),
(N'0b00d60b8d6cfb05'),
(N'0b00d60b8d57a2b9'),
(N'00-d#!b8-d6/f&#b'))V(myCol)
WHERE V.myCol LIKE '0%' --Checks starts with a 0
AND V.myCol NOT LIKE '%[^0-9A-z]%' --Checks only contains alphanumerical characters
AND LEN(V.myCol) = 16;
The second clause works as the LIKE will match any character that isn't an alphanumerical character. The NOT then (obviously) reverses that, meaning that the expression only resolves to TRUE when the value only contains alphanumerical characters.
Pattern matching in SQL Server is not awesome, and there is currently no real regex support.
The % in your pattern is what is including the special characters you show in your example. The [a-z0-9] is only matching a single character. If your character lengths are 16 and you're only interested in letters and numbers then you can include a pattern for each one:
SELECT *
FROM Table
WHERE myCol LIKE '[0][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9][a-z0-9]';
Note: you don't need the AND LEN(myCol) = 16 with this.
In Redshift I want to return fields that contain numbers or special characters EXCEPT . (anything other and a-z and A-Z)
The following gets me anything that contains a number but I need to extend this to any special character except full stop (.)
SELECT DISTINCT name
FROM table
WHERE name ~ '[0-9]'
I need something like:
SELECT DISTINCT name
FROM table
WHERE name ~ '[0-9]' OR name ~'[,#';:#~[]{}etcetc'
Sample Data:
name
john
joh1n1
j!ohn!
jo!h2n
joh.n
jo.&hn
j.3ohn
j.$9ohn
Expected Output:
name
joh1n1
j!ohn!
jo!h2n
jo.&hn
j.3ohn
j.$9ohn
You may use
WHERE name !~ '^[[:alpha:].]+$'
Here, all records that do not consist of only alphabetic or dot symbols will be returned. ^ matches the start of a string position, [[:alpha:].]+ matches one or more letters or dots and $ matches the end of string position.
If it is for PostgreSQL you may use
WHERE name SIMILAR TO '%[^[:alpha:].]%'
The SIMILAR TO operator accepts POSIX character classes and bracket expressions and wildcards, too, and requires a full string match. So, % allows any chars before any 1 char other than letter or dot ([^[:alpha:].]), and then there may also be any other chars till the end of the string.
You can do:
SELECT DISTINCT name FROM table WHERE name !~* '[a-z]'
This means: match on names that do not contain any alphanumeric character.
Operator !~* means:
Does not match regular expression, case insensitive
Edit based on the provided sample data and expected results.
If you want to match on names that contain at least one character other than an alphabetic character or a dot, then you can do:
select * from mytable where name ~* '[^a-z.]'
Demo on DB Fiddle:
with mytable(name) as (values
('john'),
('joh1n1'),
('j!ohn!'),
('jo!h2n'),
('joh.n'),
('jo.&hn'),
('j.3ohn'),
('j.$9ohn')
)
select * from mytable where name ~* '[^a-z.]'
| name |
| :------ |
| joh1n1 |
| j!ohn! |
| jo!h2n |
| jo.&hn |
| j.3ohn |
| j.$9ohn |
Assuming I have table that looks like this:
Id | Name | Age
=====================
1 | Jose | 19
2 | Yolly | 26
20 | Abby | 3
29 | Tara | 4
And my query statement is:
1) Select * from thisTable where Name <= '*Abby';
it returns 0 row
2) Select * from thisTable where Name <= 'Abby';
returns row with Abby
3) Select * from thisTable where Name >= 'Abby';
returns all rows // row 1-4
4) Select * from thisTable where Name >= '*Abby';
returns all rows; // row 1-4
5) Select * from thisTable where Name >= '*Abby' and Name <= "*Abby";
returns 0 row.
6) Select * from thisTable where Name >= 'Abby' and Name <= 'Abby';
returns row with Abby;
My question: why I got these results? How does the wildcard affect the result of query? Why don't I get any result if the condition is this Name <= '*Abby' ?
Wildcards are only interpreted when you use LIKE opterator.
So when you are trying to compare against the string, it will be treated literally. So in your comparisons lexicographical order is used.
1) There are no letters before *, so you don't have any rows returned.
2) A is first letter in alphabet, so rest of names are bigger then Abby, only Abby is equal to itself.
3) Opposite of 2)
4) See 1)
5) See 1)
6) This condition is equivalent to Name = 'Abby'.
When working with strings in SQL Server, ordering is done at each letter, and the order those letters are sorted in depends on the collation. For some characters, the sorting method is much easier to understand, It's alphabetical or numerical order: For example 'a' < 'b' and '4' > '2'. Depending on the collation this might be done by letter and then case ('AaBbCc....') or might be Case then letter ('ABC...Zabc').
Let's take a string like 'Abby', this would be sorted in the order of the letters A, b, b, y (the order they would appear would be according to your collation, and i don't know what it is, but I'm going to assume a 'AaBbCc....' collation, as they are more common). Any string starting with something like 'Aba' would have a value sell than 'Abby', as the third character (the first that differs) has a "lower value". As would a value like 'Abbie' ('i' has a lower value than 'y'). Similarly, a string like 'Abc' would have a greater value, as 'c' has a higher value than 'b' (which is the first character that differs).
If we throw numbers into the mix, then you might be surpised. For example the string (important, I didn't state number) '123456789' has a lower value than the string '9'. This is because the first character than differs if the first character. '9' is greater than '1' and so '9' has the "higher" value. This is one reason why it's so important to ensure you store numbers as numerical datatypes, as the behaviour is unlikely to be what you expect/want otherwise.
To what you are asking, however, the wildcard for SQL Server is '%' and '_' (there is also '^',m but I won't cover that here). A '%' represents multiple characters, while '_' a single character. If you want to specifically look for one of those character you have to quote them in brackets ([]).
Using the equals (=) operator won't parse wildcards. you need to use a function that does, like LIKE. Thus, if you want a word that started with 'A' you would use the expression WHERE ColumnName LIKE 'A%'. If you wanted to search for one that consisted of 6 characters and ended with 'ed' you would use WHERE ColumnName LIKE '____ed'.
Like I said before, if you want to search for one of those specific character, you quote then. So, if you wanted to search for a string that contained an underscore, the syntax would be WHERE ColumnName LIKE '%[_]%'
Edit: it's also worth noting that, when using things like LIKE that they are effected by the collations sensitivity; for example, Case and Accent. If you're using a case sensitive collation, for example, then the statement WHERE 'Abby' LIKE 'abb%' is not true, and 'A' and 'a' are not the same case. Like wise, the statement WHERE 'Covea' = 'Covéa' would be false in an accent sensitive collation ('e' and 'é' are not treated as the same character).
A wildcard character is used to substitute any other characters in a string. They are used in conjunction with the SQL LIKE operator in the WHERE clause. For example.
Select * from thisTable WHERE name LIKE '%Abby%'
This will return any values with Abby anywhere within the string.
Have a look at this link for an explanation of all wildcards https://www.w3schools.com/sql/sql_wildcards.asp
It is because, >= and <= are comparison operators. They compare string on the basis of their ASCII values.
Since ASCII value of * is 42 and ASCII values of capital letters start from 65, that is why when you tried name<='*Abby', sql-server picked the ASCII value of first character in your string (that is 42), since no value in your data has first character with ASCII value less than 42, no data got selected.
You can refer ASCII table for more understanding:
http://www.asciitable.com/
There are a few answers, and a few comments - I'll try to summarize.
Firstly, the wildcard in SQL is %, not * (for multiple matches). So your queries including an * ask for a comparison with that literal string.
Secondly, comparing strings with greater/less than operators probably does not do what you want - it uses the collation order to see which other strings are "earlier" or "later" in the ordering sequence. Collation order is a moderately complex concept, and varies between machine installations.
The SQL operator for string pattern matching is LIKE.
I'm not sure I understand your intent with the >= or <= stateements - do you mean that you want to return rows where the name's first letter is after 'A' in the alphabet?
what is difference between these two sql statements
1- select * from tblperson where name not like '[^AKG]%';
2- select * from tblperson where name like '[AKG]%';
showing same results: letter starting from a,k,g
like '[^AKG]% -- This gets you rows where the first character of name is not A,K or G. ^ matches any single character not in the specified set or a specified range of characters. There is one more negation not. So when you say name not like '[^AKG]%' you get rows where the first character of name is A,K or G.
name like '[AKG]% -- you get rows where the first character of name is A,K or G.
The wildcard character [] matches any character in a specified range or a set of characters. In your case it is a set of characters.
So both the conditions are equivalent.
You are using a double 'NOT'. The carrot '^' in your first character match is shorthand for 'not', so you are evaluating 'not like [not' AKG]% IE not like '[^AKG]%'.
1)In the first query you are using 'Not' and '^' basically it is Not twice so it cancels outs
therefore your query is 'Not Like [^AKG]' ==> 'Like [AKG]'
^ a.k.a caret or up arrow.
The purpose of this symbol is to provide a match for any characters not listed within the brackets [] , meaning that normally it wouldn't provide a result for anything that starts with AKG, but since you added the word NOT to the query , you are basically cancelling the operator, just as if you were doing in math :
(- 1) * (- 1)
I have data like this in the below column
ColA
a,b,,|c,d,e,f|l,m,,|p,q,r,s
So here I want to remove the complete data seperated by Pipe(|) if it has two consecutive commas ,,.
My output should be,
ColA
c,d,e,f|p,q,r,s
Pls help with the query.
I'll be using regexp_replace with the following example
SELECT
REGEXP_REPLACE('a,b,,|c,d,e,f|l,m,,|p,q,r,s', --source column
'.{1,3}(,,\|)', --find pattern
'', --replace with null
1, --start with position number
0, --occurance
'i') --regex match parameter
FROM dual;
Similar approach, but more scenarios addressed:
SELECT REGEXP_REPLACE('a,b,,|c,d,e,f|l,m,,|p,q,r,s', '^[^|]*,{2,3}[^|]*\|*|\|[^|]*,{2,3}[^|]*' )
FROM dual;
Components of the replacement regular expression (seperated by alternation operator)
^[^|]*,{2,3}[^|]*\|* left end or only one entry
or
\|[^|]*,{2,3}[^|]* center (always take off left pipe)
explanation:
^ is an anchor for the start of the string
[^|] is a non-pipe character
* is the 0, n quantifier
{2,3} explicit quantifier match of 2 or 3 times
| alternation operator (or)