Checking Multiple Values for a Variable

How to test multiple variables for equality against a single value?

You misunderstand how boolean expressions work; they don't work like an English sentence and guess that you are talking about the same comparison for all names here. You are looking for:

if x == 1 or y == 1 or z == 1:

x and y are otherwise evaluated on their own (False if 0, True otherwise).

You can shorten that using a containment test against a tuple:

if 1 in (x, y, z):

or better still:

if 1 in {x, y, z}:

using a set to take advantage of the constant-cost membership test (i.e. in takes a fixed amount of time whatever the left-hand operand is).

Explanation

When you use or, python sees each side of the operator as separate expressions. The expression x or y == 1 is treated as first a boolean test for x, then if that is False, the expression y == 1 is tested.

This is due to operator precedence. The or operator has a lower precedence than the == test, so the latter is evaluated first.

However, even if this were not the case, and the expression x or y or z == 1 was actually interpreted as (x or y or z) == 1 instead, this would still not do what you expect it to do.

x or y or z would evaluate to the first argument that is 'truthy', e.g. not False, numeric 0 or empty (see boolean expressions for details on what Python considers false in a boolean context).

So for the values x = 2; y = 1; z = 0, x or y or z would resolve to 2, because that is the first true-like value in the arguments. Then 2 == 1 would be False, even though y == 1 would be True.

The same would apply to the inverse; testing multiple values against a single variable; x == 1 or 2 or 3 would fail for the same reasons. Use x == 1 or x == 2 or x == 3 or x in {1, 2, 3}.

Check if multiple variables have the same value

If you have an arbitrary sequence, use the all() function with a generator expression:

values = [x, y, z]  # can contain any number of values
if all(v == 1 for v in values):

otherwise, just use == on all three variables:

if x == y == z == 1:

If you only needed to know if they are all the same value (regardless of what value that is), use:

if all(v == values[0] for v in values):

or

if x == y == z:

Query with where clause checking a variable with multiple values

It is not possible to define a list as a variable. You would have to declare your variable as a temporary table.

In your use case, you seem to be looking for dynamic sql.

declare @myList varchar(100)
set @myList = '( "Owner", "Admin", "Rule" )'
exec('SELECT * FROM product.text_data WHERE product.text_data.field_ref IN' + @myList)

Why does checking a variable against multiple values with `OR` only check the first value?

("Jesse" or "jesse")

The above expression tests whether or not "Jesse" evaluates to True. If it does, then the expression will return it; otherwise, it will return "jesse". The expression is equivalent to writing:

"Jesse" if "Jesse" else "jesse"

Because "Jesse" is a non-empty string though, it will always evaluate to True and thus be returned:

>>> bool("Jesse")  # Non-empty strings evaluate to True in Python
True
>>> bool("")  # Empty strings evaluate to False
False
>>>
>>> ("Jesse" or "jesse")
'Jesse'
>>> ("" or "jesse")
'jesse'
>>>

This means that the expression:

name == ("Jesse" or "jesse")

is basically equivalent to writing this:

name == "Jesse"

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In order to fix your problem, you can use the in operator:

# Test whether the value of name can be found in the tuple ("Jesse", "jesse")
if name in ("Jesse", "jesse"):

Or, you can lowercase the value of name with str.lower and then compare it to "jesse" directly:

# This will also handle inputs such as "JeSSe", "jESSE", "JESSE", etc.
if name.lower() == "jesse":

Typescript If statement with multiple value matches for the same variable

Syntactically, you can use switch instead of if to test for multiple values using repeating cases:

switch (x) {
  case 5:
  case "":
  case undefined:
    // do something
    break;
}

But this is rarely done.

To programatically test for multiple values, you can put the values in an array and check that it includes your argument value using indexOf:

if ([5, "", undefined].indexOf(x) >= 0) {
  ...
}

Note that this will create the values array each time, so if this check repeats you might want to create the array once, elsewhere, and reuse it.

const values = [5, "", undefined];

// elsewhere
if (values.indexOf(x) >= 0) {
  ...
}

In fact, if the number of values to test is large, you might want to put them in a Set and check that it has them, as this is faster than testing against an array:

const values = new Set(5, "", undefined);

// elsewhere
if (values.has(x)) {
  ...
}

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