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How to declare a variable in MySQL?
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For any person using @variable in concat_ws function to get concatenated values, don't forget to reinitialize it with empty value. Otherwise it can use old value for same session.
Set @Ids = '';
select
@Ids := concat_ws(',',@Ids,tbl.Id),
tbl.Col1,
.....
Properties vs Methods
...hod, but otherwise this answer is not accurate.
– Hal50000
Nov 10 '16 at 23:18
The first sentence explains all. Bravo....
Why does the JavaScript need to start with “;”?
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I would say since scripts are often concatenated and minified/compressed/sent together there's a chance the last guy had something like:
return {
'var':'value'
}
at the end of the last script without a ; on the end. If you have a ; at the start on yours,...
Reading a huge .csv file
...f_list.append(df_chunk)
# Merge all dataframes into one dataframe
X = pd.concat(df_list)
# Delete the dataframe list to release memory
del df_list
del df_chunk
share
|
improve this answer
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Array_merge versus + [duplicate]
... instead using two new functions we wrote. "array_merge_by_key" and "array_concat" instead of a single function with a heuristic that tries to guess at what you want
– Yuliy
Jul 28 '14 at 0:38
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Using “like” wildcard in prepared statement
...meter is itself interpreted as a mix of data and control instructions. SQL concatenation occurs before it is interpreted and preserves the vulnerability. The IEEE Center for Secure Design says to Strictly Separate Data and Control Instructions, and Never Process Control Instructions Received from Un...
How can I see the specific value of the sql_mode?
...--------------------------------------------------------------+
| PIPES_AS_CONCAT,ANSI_QUOTES,IGNORE_SPACE,ORACLE,NO_KEY_OPTIONS,NO_TABLE_OPTIONS,NO_FIELD_OPTIONS,NO_AUTO_CREATE_USER |
+------------------------------------------------------------------------------------------------------------------...
How can I combine two HashMap objects containing the same types?
...ual keys and values, so you'll need to use a loop or Map.forEach. Here we concatenate strings for duplicate keys:
map3 = new HashMap<>(map1);
for (Map.Entry<String, String> e : map2.entrySet())
map3.merge(e.getKey(), e.getValue(), String::concat);
//or instead of the above loop
map...
log4j logging hierarchy order
...tatic int OFF_INT = Integer.MAX_VALUE;
public final static int FATAL_INT = 50000;
public final static int ERROR_INT = 40000;
public final static int WARN_INT = 30000;
public final static int INFO_INT = 20000;
public final static int DEBUG_INT = 10000;
public static final int TRACE_INT = 5000;
pub...
private final static attribute vs private final attribute
...eful use case scenario for that. This could be beneficial if you have like 50000 int vars in a class. Even in this case, this would save up 200kb of memory. Since we are talking Java, this seems totally irrelevant. In case of memory critical devices, a decent C or C++ compiler would inline those int...