大约有 6,100 项符合查询结果（耗时：0.0362秒） [XML]
MySQL remove all whitespaces from the entire column
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To replace all spaces :
UPDATE `table` SET `col_name` = REPLACE(`col_name`, ' ', '')
To remove all tabs characters :
UPDATE `table` SET `col_name` = REPLACE(`col_name`, '\t', '' )
To remove all new line characters :
UPDATE `table` SET `col_name` = REP...
How to filter SQL results in a has-many-through relation
Assuming I have the tables student , club , and student_club :
13 Answers
13
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SQLite select where empty?
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It looks like you can simply do:
SELECT * FROM your_table WHERE some_column IS NULL OR some_column = '';
Test case:
CREATE TABLE your_table (id int, some_column varchar(10));
INSERT INTO your_table VALUES (1, NULL);
INSERT INTO your_table VALUES (2, '');
INSERT INTO your_t...
How to COUNT rows within EntityFramework without loading contents?
I'm trying to determine how to count the matching rows on a table using the EntityFramework.
7 Answers
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URL Encoding using C#
...asy.
As for Linux versus windows, there are some characters that are acceptable in Linux that are not in Windows, but I would not worry about that, as the folder name can be returned by decoding the Url string, using UrlDecode, so you can round trip the changes.
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Good way to use table alias in Update statement?
I'm using SQL Server, and trying to update rows from within the same table. I want to use a table alias for readability.
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How to implement a Map with multiple keys? [duplicate]
...nother solution is to use Google's Guava
import com.google.common.collect.Table;
import com.google.common.collect.HashBasedTable;
Table<String, String, Integer> table = HashBasedTable.create();
The usage is really simple:
String row = "a";
String column = "b";
int value = 1;
if (!table.c...
Finding duplicate values in MySQL
I have a table with a varchar column, and I would like to find all the records that have duplicate values in this column. What is the best query I can use to find the duplicates?
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How to reshape data from long to wide format
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Another option if performance is a concern is to use data.table's extension of reshape2's melt & dcast functions
(Reference: Efficient reshaping using data.tables)
library(data.table)
setDT(dat1)
dcast(dat1, name ~ numbers, value.var = "value")
# name 1 ...
Whether a variable is undefined [duplicate]
....page_name ? "&page_name=" + opt.page_name : "");
retval.push( opt.table_name ? "&table_name=" + opt.table_name : "");
retval.push( opt.optionResult ? "&optionResult=" + opt.optionResult : "");
return retval.join("");
}
my_url("?z=z", { page_name : "pageX" /* no table_name ...