This question already has an answer here:
Difference between substring in Postgresql
(1 answer)
Closed 2 years ago.
I've noticed that Postgres allows me to use SUBSTR or SUBSTRING. Both produce the same results. Is there a difference in the two?
There are some differences at least in syntax:
substring(string [from int] [for int])
substring(string from pattern)
substring(string from pattern for escape)
and
substr(string, from [, count])
See details in https://www.postgresql.org/docs/12/functions-string.html
Related
This question already has answers here:
Python Regex Engine - "look-behind requires fixed-width pattern" Error
(3 answers)
Regex to get the word after specific match words
(5 answers)
Closed 8 months ago.
This post was edited and submitted for review 8 months ago and failed to reopen the post:
Original close reason(s) were not resolved
My code below match the first word after one expression "let" :
(?<=\blet\s)(\w+)
What I need is to match the first word after a specific expressions, "let", "var", "func"
Input text:
let name: String
var age: Int
func foo() {
//...
Expected:
name
age
foo
Here is an image for clarity:
Since some regex flavors do not allow using groups inside lookbehinds and alternatives of different length, it is safe to use a non-capturing group with the lookbehind as alternatives:
(?:(?<=\blet\s)|(?<=\bvar\s)|(?<=\bfunc\s))\w+
Here, (?:...|...|...) is a non-capturing group matching one of the three alternatives: (?<=\blet\s), (?<=\bvar\s) and (?<=\bfunc\s).
This question already has an answer here:
Firestore Query Properties with special characters
(1 answer)
Closed 2 years ago.
With the following document, how would you escape the where query ?
/posts/abc
users: [map]
abc.def: 4
firestore().collection('posts').where('users.abc.def' , '>' , 0)
Is there a way to escape the . ?
Thanks
As #kmoser mentioned in the comment above, the solution is to use FieldPath
firestore().collection('posts').where(new firestore.FieldPath('users', 'abc.def'), '>' , 0)
This question already has an answer here:
Why do escape characters in regex mismatch?
(1 answer)
Closed 3 years ago.
https://imgsa.baidu.com/forum/w%3D580/sign=bbcf762fa986c91708035231f93c70c6/10c17c3e6709c93d5eca9c20913df8dcd0005407.jpg
I have implemented fuzzy searching using RegEx as shown below. I just want to get '1.0' and '1.01', But the results show figures such as '1.0' '1.01' '100' '100.10' and '110.11'. Why does 1.0 match 100 and 100.10? How can I only get 1.0 and 1.01?
db.getCollection ("CE").find (
{
"ID": /1.0/
}
);
the . in regex means any character, so 1.0 means a 1 followed by any character, followed by a 0. So 100, 1.0 , 1a0, etc are valid matches.
What you need to do is to escape the dot with a \. So replace your regex with 1\.0. Or with ^1\.0 if you want to only match strings that start with 1.0.
This question has probably been answered many times, please feel free to delete the question.
This question already has answers here:
Why do integers in PowerShell compare by digits?
(4 answers)
Closed 4 years ago.
In powershell, when I add string + array the result is a string, but when I add array + string the result is an array? Why is that?
PowerShell converts the second operand to the type of the first operand (if it can).
This question already has answers here:
What do all of Scala's symbolic operators mean?
(11 answers)
Closed 8 years ago.
What does :: mean here ?
listeners ::= listener
list = num :: list
Specially I don't understand the "::" operator.
Its the list cons operator. It creates a new list whose head is first argument and whose tail is contents of the second argument.