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Replacing blank values (white space) with NaN in pandas
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12 Answers
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MySQL: @variable vs. variable. What's the difference?
...nitialize this variable with a SET statement or inside a query:
SET @var = 1
SELECT @var2 := 2
When you develop a stored procedure in MySQL, you can pass the input parameters and declare the local variables:
DELIMITER //
CREATE PROCEDURE prc_test (var INT)
BEGIN
DECLARE var2 INT;
SET var...
How do you know when to use fold-left and when to use fold-right?
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105
You can transfer a fold into an infix operator notation (writing in between):
This example fo...
How can I convert an Integer to localized month name in Java?
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Using “like” wildcard in prepared statement
... "SELECT * FROM analysis WHERE notes LIKE ? ESCAPE '!'");
pstmt.setString(1, notes + "%");
or a suffix-match:
pstmt.setString(1, "%" + notes);
or a global match:
pstmt.setString(1, "%" + notes + "%");
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How to use enums as flags in C++?
...efine bit operators for the enum, as:
enum AnimalFlags
{
HasClaws = 1,
CanFly = 2,
EatsFish = 4,
Endangered = 8
};
inline AnimalFlags operator|(AnimalFlags a, AnimalFlags b)
{
return static_cast<AnimalFlags>(static_cast<int>(a) | static_cast<int>(b));
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What is the significance of 1/1/1753 in SQL Server?
Why 1753? What do they have against 1752? My great great great great great great great grandfather would be very offended.
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Add unique constraint to combination of two columns
...TER TABLE dbo.yourtablename
ADD CONSTRAINT uq_yourtablename UNIQUE(column1, column2);
or
CREATE UNIQUE INDEX uq_yourtablename
ON dbo.yourtablename(column1, column2);
Of course, it can often be better to check for this violation first, before just letting SQL Server try to insert the row and...
Passing functions with arguments to another function in Python?
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Do you mean this?
def perform( fun, *args ):
fun( *args )
def action1( args ):
something
def action2( args ):
something
perform( action1 )
perform( action2, p )
perform( action3, p, r )
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Check existence of input argument in a Bash shell script
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