大约有 1,832 项符合查询结果（耗时：0.0295秒） [XML]
How to add column if not exists on PostgreSQL?
...lumn_name> <column_type>;
EXCEPTION
WHEN duplicate_column THEN RAISE NOTICE 'column <column_name> already exists in <table_name>.';
END;
END;
$$
You can't pass these as parameters, you'll need to do variable substitution in the string on the clie...
How to initialize HashSet values by construction?
..." and "b". Note that while in JDK 8 this does return a HashSet, the specification doesn't guarantee it, and this might change in the future. If you specifically want a HashSet, do this instead:
Set<String> set = Stream.of("a", "b")
.collect(Collectors.toCollection(Hash...
How do I revert all local changes in Git managed project to previous state?
...d $i to a" ;done > /dev/null
$ git reset --hard HEAD^^ > /dev/null
$ cat a
foo
b
c
$ git reflog
145c322 HEAD@{0}: HEAD^^: updating HEAD
ae7c2b3 HEAD@{1}: commit: Append e to a
fdf2c5e HEAD@{2}: commit: Append d to a
145c322 HEAD@{3}: commit: Append c to a
363e22a HEAD@{4}: commit: Append b to ...
How to print the ld(linker) search path
...g makefile from configure script or from CMakeLists.txt or even more complicated ones such as vala or srt. It's hard for me to modify ld search path in such cases
– kenn
Sep 9 '14 at 10:18
...
Unique constraint on multiple columns
...1) NOT NULL,
[ID] [int] NOT NULL,
[name] [nvarchar](50) NULL,
[cat] [nvarchar](50) NULL,
CONSTRAINT [PK_Table_1] PRIMARY KEY CLUSTERED
(
[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
...
Confused by python file mode “w+”
...
with open('somefile.txt', 'w+') as f:
# Note that f has now been truncated to 0 bytes, so you'll only
# be able to read data that you write after this point
f.write('somedata\n')
f.seek(0) # Important: return to the top of the file before reading, otherwise you'll just read an emp...
In Git, how can I write the current commit hash to a file in the same commit
...=${branch_name##refs/heads/}
branch_name=${branch_name:-HEAD} # 'HEAD' indicates detached HEAD situation
# Write it
echo -e "prev_commit='$commit_hash'\ndate='$commit_date'\nbranch='$branch'\n" > gitcommit.py
Now the only thing we need is a tool that converts prev_commit,branch pair to a real ...
Ruby: Merging variables in to a string
...the argument number and shuffle them around:
'The %3$s %2$s the %1$s' % ['cat', 'eats', 'mouse']
Or specify the argument using hash keys:
'The %{animal} %{action} the %{second_animal}' %
{ :animal => 'cat', :action=> 'eats', :second_animal => 'mouse'}
Note that you must provide a va...
Bash script - variable content as a command to run
...
You just need to do:
#!/bin/bash
count=$(cat last_queries.txt | wc -l)
$(perl test.pl test2 $count)
However, if you want to call your Perl command later, and that's why you want to assign it to a variable, then:
#!/bin/bash
count=$(cat last_queries.txt | wc -l)
v...
In R, how to get an object's name after it is sent to a function?
...
Perhaps it should be: print.foo=function(x){ cat(deparse(substitute(x))) } or print.foo=function(x){ print(deparse(substitute(x)), quote=FALSE) }
– IRTFM
Nov 30 '13 at 18:58
...