[SOLVED] Substrings in ZMSQL
lazarus / 63-Database

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maurobio · 2021-09-20 22:13

Dear ALL,

Many dialects of SQL (MySQL, SQLite, etc.) have a handy SUBSTR()
function which extract a substring from a string (starting at any
position), for example:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i SELECT
SUBSTR(CustomerName, 2, 5) AS ExtractString FROM Customers;
However, the ZMSQL library (https://wiki.freepascal.org/ZMSQL) offers
two rather unusual variations of this function, as follows:

Quotesubstr_after(source, substring) Returns the part of source that
comes after substring. If substring is not found an empty string is
returned.

substr_before(source, substring) Returns the part of source that comes
before substring. If substring is not found an empty string is
returned.
I do not understand how these functions work and have not been able to
find any examples. Could some one provides me with a few hints?

Thanks in advance!

With best wishes,

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paweld · 2021-09-21 05:50

mid(expression, from, count) : https://github.com/git-
bee/janSQL/blob/master/doc/6_functions.md#64-string-functions
Code: SQL  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i SELECT
string_col, mid(string_col, 2, 5) FROM TABLE

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maurobio · 2021-09-21 11:21

Dear @paweld,

Thanks a lot, it is now clear and it works fine!

With best wishes,