Escape sequences are a general technique to represent characters that are not possible to represent directly. In QlikView the need is mainly for quotation marks, but in the general case it could also be strange characters, tabs, and newlines. How this is handled in QlikView is explained in this post.
When writing a string in QlikView, it must usually be enclosed in single quotes. But what if you want to use a single quote inside the string? The following will not work:
Setvariable = 'This year's number';
The reason is that the apostrophe in the word year’s will be interpreted as the single quote that ends the string. So what should you do instead?
One solution that I have seen often in the community is to hard-code it using the Chr() function:
Both these work fine, but they are maybe not very elegant. Instead, I would suggest one of the following methods. First, you can often use a different delimiter:
Setvariable = [This year's number];
As you can see, the Set statement can also use square brackets (or double quotes) as delimiters. Hence, if you just use a delimiter that is different from what you have in the string, it will work. The same is true if you need to load from a file with a name that contains single quotes or square brackets. Just make sure you quote it using double quotes (which is a character that shouldn't exist in file names):
Load … From "This year's numbers [3].xlsx"
But there is a second way this problem can be solved. An escape sequence:
Letvariable = 'This year''s number';
The Let statement is different from the Set statement in that you must use single quotes as delimiter for literals. So you need to use an escape sequence instead: Just write the single quote twice, and the two characters will not be interpreted as a string delimiter, but instead as a single instance of the character itself. The same method can be used in other places also, e.g. in Set Analysis. The following expression is a correct one picking out the records from Robert's unit:
Sum({1<Unit={'Robert''s unit'}>} Amount)
An escape sequence can be used for double quotes and square brackets, too. So if you have a field name that contains double quotes, for instance Name”5, you can load it either by using square brackets or by escaping the double quote:
[Name"5]asField1, "Name""5"asField2,
If the field name contains square brackets, e.g. a field called Name[5], only the right bracket needs to be escaped. Such a field can be loaded in either of the two following ways:
"Name[5]"asField1, [Name[5]]]asField2,
With this, I hope you got some ideas about how to deal with odd characters and strangely named fields.
You're right Henric (as always). It was a bit difficult to detect, as I only had the terminating semicolon getting stored with the string.
Again misled by the QV documentation/help that says, Theletstatement, in opposition to the set statement, evaluates the expression on the right side of the '=' (indeed, from the LET help) I thought not evaluating the right hand side meant notdeciding whether this is a string or not. Just look for the terminating semicolon. Sorry. QV is still very capable at dodging expectations
This is a very creative example of QV script parser behavior with respect to quoting:
SET vVariable = ]/*[;
This syntax is perfectly valid. It will only store the initial closing bracket in vVariable. The opening bracket will disappear due to the opening comment, but the semicolon will function as expected (?). It will terminate the current statement. All subsequent (non-wacky) statements will execute as expected.
Not true: the comment will wipe out all remaining script text (or until it encounters its counterpart). The syntax checker however doesn't obey the same rules as the script engine, it seems.
Lot of useful information concernig quotation, but not my quotation problem.
I've a variable containing a text starting with a single quote (chr(39)).
I'm trying to use this variable (within $()) as literal in a Load statement, but as literals should come in single quotes it doesn't work.
Here is my code:
The QV parser inserts Escape sequence trying to solve the problem.
My variable vFile contains a single quote:
But the error comes with following debug information, the literal is starting with a triple single quote:
According to previous information, I would assume that the second and third quote would resolve as Escape sequence, but that doesn't work. My guess is doesn't work because it's at the beginning of the literal.
My simple solution is to replace the single quote by quotation mark, that works.
However my style is 'perfect and simple' solutions: so I'm still looking for a better wat to solve this.
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