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.
Related
I need to find rows where the phone number field contains unexpected characters.
Most of the values in this field look like:
123456-7890
This is expected. However, we are also seeing character values in this field such as * and #.
I want to find all rows where these unexpected character values exist.
Expected:
Numbers are expected
Hyphen with numbers is expected (hyphen alone is not)
NULL is expected
Empty is expected
Tried this:
WHERE phone_num is not like ' %[0-9,-,' ' ]%
Still getting rows where phone has numbers.
from https://regexr.com/3c53v address you can edit regex to match your needs.
I am going to use example regex for this purpose
select * from Table1
Where NOT REGEXP_LIKE(PhoneNumberColumn, '^[+]*[(]{0,1}[0-9]{1,4}[)]{0,1}[-\s\./0-9]*$')
You can use translate()
...
WHERE translate(Phone_Number,'a1234567890-', 'a') is NOT NULL
This will strip out all valid characters leaving behind the invalid ones. If all the characters are valid, the result would be NULL. This does not validate the format, for that you'd need to use REGEXP_LIKE or something similar.
You can use regexp_like().
...
WHERE regexp_like(phone_num, '[^ 0123456789-]|^-|-$')
[^ 0123456789-] matches any character that is not a space nor a digit nor a hyphen. ^- matches a hyphen at the beginning and -$ on the end of the string. The pipes are "ors" i.e. a|b matches if pattern a matches of if pattern b matches.
Oracle has REGEXP_LIKE for regex compares:
WHERE REGEXP_LIKE(phone_num,'[^0-9''\-]')
If you're unfamiliar with regular expressions, there are plenty of good sites to help you build them. I like this one
How to avoid selecting row which has special symbol like mentioned below .
We can use range of ASCII character as below. CHAR(n) returns character value of integer ASCII code n
SELECT *
FROM yourTable
WHERE ID NOT LIKE '%['+CHAR(32) +'-'+CHAR(126)+']%'
OR Name NOT LIKE '%['+CHAR(32) +'-'+CHAR(126)+']%';
Refer ASCII characters
You could use SQL Server's enhanced LIKE operator:
SELECT *
FROM yourTable
WHERE ID NOT LIKE '%[^A-Za-z0-9_-]%' AND Name NOT LIKE '%[^A-Za-z0-9_-]%';
This would select only rows where both ID and Name columns do not contain any special characters. Special characters here are defined as anything other alphanumeric, underscore, and hyphen.
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?
I want to find all rows for which values in string column does not possess certain characters (to be specific [a-Z0-9 \t\n]) how can I do it in sql ?
I tried to do it with like operator
SELECT ***
where column like '%[^ a-Z0-9 \t\n]%'
however, it does not work and I get rows that possess characters and numbers.
To fetch all records that contain any characters other than alphabets, numbers, spaces, tabs and new-line delimiters:
SELECT ***
WHERE column like '%[^A-Za-z0-9 \t\n]%'
Note that [^A-Za-z0-9 \t\n] represents anything other than alphanumeric characters, spaces, tabs, and new line delimitters.
Your logic is inverted. I think you want:
where column not like '%[^ a-Z0-9 \t\n]%'
I don't think that SQL Server interprets \t and \n as special characters. You may need to insert the actual values for the characters. (See here.)
SELECT ***
WHERE column like '%[^A-Za-z0-9 \t\n]%'
I need help with the regex pattern to add N before all string values in sql-statements
For example:
Before: SELECT * FROM table WHERE column = '123';
After: SELECT * FROM table WHERE column = N'123';
In that example, I can use this pattern: '[^']+'. However, I need help with pattern for this example:
Before: SELECT * FROM table WHERE column1 = 'One''Two' AND column2 = 'abc';
After: SELECT * FROM table WHERE column1 = N'One''Two' AND column2 = N'abc';
If there's a double '', it should skip those.
Information about my problem: You must precede all Unicode strings with a prefix N when you deal with Unicode string constants in SQL Server
Well, you could use something like this to satisfy the above (provided whatever you're using to apply it supports a negative lookbehind:
(?<!')'[\w]+?'
It's using a negative lookbehind to exclude captures between ' and ' that are preceded by another '. You may have to adapt the \w if you required spaces/other characters.
Edit (Updated answer to include your extra strings from the comments):
You could try:
(?<=\s)'.*?'
Which will capture zero or more characters occurring between ' characters (ungreedy), and uses a positive lookbehind to ensure the first ' is preceded by a space character, which should satisfy all the strings you've listed.
You could optionally add a negative lookahead on the end (?!\w) to skip over the ' in O'Connor.