The Difference Between 'And' and '&&' in SQL

The difference between 'AND' and '&&' in SQL

For mySQL: The manual is not saying it explicitly, but they are listed as identical:

AND, &&

Logical AND. Evaluates to 1 if all operands are nonzero and not NULL, to 0 if one or more operands are 0, otherwise NULL is returned.

The operator precedence page also makes no distiction.

Oracle SQL - Difference between AND & OR operators

AND operator mean both (department_id = 10) is TRUE also (Department_ID = 20 ) is TRUE, result is TRUE

OR operator mean either (department_id = 10) is TRUE or (Department_ID = 20 ) is TRUE, result is TRUE

What is the differences between & and && in EF Core

but what about EF? Is there any differences between & and && (same for | and ||)? performance-wise!

Yes, there is.

First, sometimes EF Core uses client evaluation, so it can't be short-circuited.

Second, even when using server evaluation, EF Core translates them differently. For instance, here is the translation for SqlServer:

LINQ             SQL
==============   ============ 
expr1 && expr2   expr1 AND expr2
expr1 & expr2    (expr1 & expr2) = 1

Whether this affects the performance depends of the database query optimizer, but the first looks generally better. And some database providers which has no native support for bool type might generate quite inefficient translation or even fail to translate the & / | predicates.

Shortly, preferably always use logical && and || operators in LINQ queries.

Is there a difference between and vs AND

MySQL is not case sensitive, at least for keywords

oracle sql - using double ampersand (&&) and double dot (..)

@Gary_W has covered the difference between a single and a double ampersand.

The double period is perhaps slightly less obvious. From the SQL*Plus documentation:

If you wish to append characters immediately after a substitution variable, use a period to separate the variable from the character.

If you had a single period:

&&DATABASE_ONE.TABLE_ONE

then that period would be treated as the terminator for the substituion variable name, and would be consumed in the process. Say the value you entered was 'HR'; the substitution would be:

old:select &&DATABASE_ONE.TABLE_ONE from dual
new:select HRTABLE_ONE from dual

select HRTABLE_ONE from dual

As you can see, there is now no period between the schema and table names, giving you a combined identifier which will not represent what you intended.

With the form you have:

&&DATABASE_ONE..TABLE_ONE

the second period is the 'normal' one that sits between those two elements; once the first has been consumed by the substitution, the second remains to fulfil that function:

old:select &&DATABASE_ONE..TABLE_ONE from dual
new:select HR.TABLE_ONE from dual

select HR.TABLE_ONE from dual

What is the difference between & and && in Java?

& <-- verifies both operands

&& <-- stops evaluating if the first operand evaluates to false since the result will be false

(x != 0) & (1/x > 1) <-- this means evaluate (x != 0) then evaluate (1/x > 1) then do the &. the problem is that for x=0 this will throw an exception.

(x != 0) && (1/x > 1) <-- this means evaluate (x != 0) and only if this is true then evaluate (1/x > 1) so if you have x=0 then this is perfectly safe and won't throw any exception if (x != 0) evaluates to false the whole thing directly evaluates to false without evaluating the (1/x > 1).

EDIT:

exprA | exprB <-- this means evaluate exprA then evaluate exprB then do the |.

exprA || exprB <-- this means evaluate exprA and only if this is false then evaluate exprB and do the ||.

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