I have a table with a column where I have data stored this way:
1:29,3:20,5:0,4:0,2:76
I want to make a query request in PHP (or MySQL in general) and get rows where there is a number less than 10 after the " : ".
Therefore, in this case I have ( 29 , 20 , 0 , 0 , 76 ), and because I have a number less than 10, I will want to take this row.
In general, storing comma separated values is not considered a good design in SQL, as it leads to violation of data normalization rules and in addition faces many other issues. But since you have already done it and want a regex solution to your problem, you can use this regex,
:[0-9](,|$)
Here is a demo
In mysql you can write a query like this,
select * from tablename where columnname regexp ':[0-9](,|$)';
This will give you rows where at least one comma separated value is less than ten following a colon.
Related
This question already has answers here:
Which is faster — INSTR or LIKE?
(4 answers)
Closed 3 months ago.
I have a table with a column that stores a random string like this:
example_id = qwhs77gt65g7*
Now some of the data on that column has asterisks(*) while others don’t have one.
I need to select those that has one. I’m using this query:
SELECT example_id FROM example_tbl WHERE example_id LIKE ‘%*%’
Now this is usually not a problem but I’m querying millions of rows and as I understand LIKE operator is affecting my performance. It takes hours to complete the query
My question is whats the alternative to the LIKE operator?
PS the asterisks is always at the end of the string. I dont know if that can help
Since you're mentioning "The asterisks are always at the end" then you can try
WHERE example_id LIKE '%*'.
This will finds any values that end with "*"
OR
Is to search for sub-string in columns of the table.
The one way to achieve it to use instr() function, instr() function takes 3 parameters in account .
Syntax : instr( rank, string, sub_string )
rank :
Integer type expression giving the position corresponding to the 1st
character in the string from which the sub-string search begins.
String : String is your text.
sub_string : The substring which you
are looking for. The instr() returns 0 if it does not find the
match.
Now how to apply this to the table?. As instr() function is of x3 so its simple to apply.
eg : Filter[ZCT] Where instr(1,ALLOTEDTO,”Ram”) <> 0.
where 1 is the start position to look for sub-string , ALLOTEDTO is column name which consist of String and last parameter is sub-string itself. This will give you all records from table where ALLOTEDTO column consist sub-string “Ram”
which is equivalent to.
Select * from ZCT where ALLOTEDTO like ‘%Ram%’.
Note: Instr() function is case sensitive so always use the upper-case or lower-case function with it.
How to display the column desc order when the column having spacial chars in mysql
I am using the follow query but not display correctly
SELECT quotation_pno FROM crm_quotation order by quotation_pno desc
My output coming like this
quotation_pno
PT/17/999
PT/17/1533
PT/17/1532
PT/16/1531
I want my output like this
quotation_pno
PT/17/1533
PT/17/1532
PT/17/999
PT/16/1531
Please help me
I'd argue, that the output is correct, but your assumptions are not. It looks to me, as if quotation_pno is some kind of textual column, right?
The sorting assumes, that you want to sort text and this works this way:
Set i to 0
Compare the i-th character of two strigns
If they are the same and the end is not reached, increase i by 1 and proceed with step 2
Otherwise order the two strings according to the value at the i-th position
(There are some things elided and the pseudocode is boiled down to the very basic, needed to understand the principle).
Applied to your example this means, when the comparison compares PT/17/999 and PT/17/1533 it looks at the characters 0 to 5 and "sees" that they are equal. When it compares the characters at position 6, they are '9' and '1'. Since the character '9' is considered to be greater than '1', PT/17/999 is placed before PT/17/1533.
How to solve the issue?
There are some ways coming into my mind, that will allow you to achieve the desired sort order.
First, you could prepend the numbers with zeros. This will allow you to re-use most of your existing structure, but will result either in very many zeros, or a system that is somehow limited, since you will be restricted to the number of digits you decided to use (or the sort will fail again).
The second possibility is, to store the parts in (additional) numerical columns in the table, e.g. one for year and one for the order number in this year. This is the more flexible approach, but involves more changes.
I have a large mysql database which is about 10gb large. One of the tables in the database is called
clients
In that table there is a colum named
case
The date this client is created is mixed into the number within this column.
Here is an example of an entry in case
011706-0001
The 06 part means this client was created in 2006. I need to pull all the clients that were created in 2015 and 2016. So I need to query for anything that case has a 15 or 16 before the dash.
For example, 000015-0000 or 000016-0000
Is there a way to do this with only mysql? My thought process was I would have to query the whole column then use php to preg_match()
I am worried that based on the size of the database this would cause problems.
To locate rows that have a case column value that contains '06-' (the characters 0 and 6 followed by a dash ...
One option is to use a LIKE comparison operator:
SELECT ...
FROM clients t
WHERE t.case LIKE '%06-%'
ORDER BY ...
The percent sign characters are wildcards in the LIKE comparison, which match any number of characters (zero, one or more.)
MySQL will need to evaluate that condition for every row in the table. MySQL can't make use of an index range scan operation with that.
SELECT ...
FROM clients t
WHERE t.case LIKE '%15-%'
OR t.case LIKE '%16-%'
ORDER BY ...
That will evaluate to true for any values that include the sequence of three characters '15-' or '16-'.
If there's a more standard format for the values in the case column, where the value always starts with exactly six characters representing date 'mmddyy-nnnnn' and you only want to match the 5th thru 7th characters, you could use the underscore wildcard character which matches any one character (in the LIKE comparison) for example... using four underscores
t.case LIKE '____16-%'
Or you could use a SUBSTR function to extract the three characters from the case value, and perform an equality comparison...
SUBSTR(t.case,5,3) = '15-'
SUBSTR(t.case,5,3) IN ('15-','16-')
It's also possible to make use of a REGEXP comparison in place of the LIKE comparison.
In terms of performance, all of the above approaches are going to need to crank through every row in the table, to evaluate the comparison condition.
If that date value was stored as a separate column, as a DATE datatype, and there was an index with that as the leading column, then MySQL could make effective use of a range scan operation, for a query like this...
WHERE t.casedate >= '2015-01-01'
AND t.casedate < '2017-01-01'
I need help with a query. I am taking input from a user where they enter a range between 1-100. So it could be like 30-40 or 66-99. Then I need a query to pull data from a table that has a high_range and a low_range to find a match to any number in their range.
So if a user did 30-40 and the table had entries for 1-80, 21-33, 32-40, 40-41, 66-99, and 1-29 it would find all but the last two in the table.
What is the easiest why to do this?
Thanks
If I understood correctly (i.e. you want any range that overlaps the one entered by the user), I'd say:
SELECT * FROM table WHERE low <= $high AND high >= $low
What I understood is that the range is stored in this format low-high. If that is the case, then this is a poor design. I suggest splitting the values into two columns: low, and high.
If you already have the values split, you can use some statement like:
SELECT * FROM myTable WHERE low <= $needleHigherBound AND high >= $needleLowerBound
If you have the values stored in one column, and insist they stay so, You might find the SUBSTRING_INDEX function of MySQL useful. But in this case, you'll have to write a complicated query to parse all the values of all the rows, and then compare them to your search values. It seems like a lot of effort to cover up a design flaw.
I'd like to generate a long list of 9-digits sequences.
Let's call them ID.
So each ID is unique and the main purpose is to have them all really different. It is unacceptable to have 2 IDs which differs by 1 or 2 digits in sequence.
Do you have any ideas how to implement it without comparing each new generated ID with each previously generated?
Probably there is some algorithm already or simple MYSQL function to compare how close those strings are?
You could try the following formula for your ID's - you would only need to check that the ID value doesn't already exist in the table (salt is a constant between 0 and 100 that doesn't ever change once you pick a value - I would recommend using a prime number, and definitely not 0):
ID = random integer * 101 + salt;
This generates ID values like the following (for salt = 73):
469956305
017775467
001195913
913620520
156482807
577463533
470183959
049290800
078643925
141526626
If you take any two of these ID values and compare them, you'll notice that no two numbers differ by only one or two digits in sequence. I wrote a script to compare all possible ID values between 0 and 3000000, and there were no two ID values of this form differing by 1 or 2 digits in sequence. If you want to test it out yourself, here's the script I used (in C#): http://ideone.com/lFHnlX - I reduced the upper limit because of timeout on IDEone.
You want to get away with not-checking for uniqueness and you don't want IDs to be similar? Then you're really looking for UUIDs/GUIDs.
MySQL's built-in uuid() function will get you there.
As Robert Harvey points out, UUIDs are alphanumeric (not numeric) and longer than 9 characters, but you're going to have to sacrifice something – you cannot satisfy all of your constraints simultaneously.