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How do I alter the position of a column in a PostgreSQL database table?
... tablename (column defs go here);
insert into tablename (col1, col2, col3) select col1, col2, col3 from oldtable;
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Two single-column indexes vs one two-column index in MySQL?
... the statement I provided.
Additionally, MySQL can only use one index per SELECT so a covering index would be the best means of optimizing your queries.
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The difference between bracket [ ] and double bracket [[ ]] for accessing the elements of a list or
...urn the ith sequential element of x.
For lists, one generally uses [[ to select any single element, whereas [ returns a list of the selected elements.
The [[ form allows only a single element to be selected using integer or character indices, whereas [ allows indexing by vectors. Note though tha...
二维码的生成细节及原理 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...映射成一个字符索引表。如下所示：（其中的SP是空格，Char是字符，Value是其索引值） 编码的过程是把字符两两分组，然后转成下表的45进制，然后转成11bits的二进制，如果最后有一个落单的，那就转成6bits的二进制。而编码模...
How to detect input type=file “change” for the same file?
I want to fire an event when the user select a file. Doing so with .change event it works if the user changes the file every time.
...
How do I enter RGB values into Interface Builder?
... enter RGB or Hex color values for backgrounds in Interface Builder? I can select predefined colors but I would like to manually enter in RGB values. Where can I do this?
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The ViewData item that has the key 'MY KEY' is of type 'System.String' but must be of type 'IEnumera
... same code used before, so repeat this:
var db = new DB();
IEnumerable<SelectListItem> basetypes = db.Basetypes.Select(
b => new SelectListItem { Value = b.basetype, Text = b.basetype });
ViewData["basetype"] = basetypes;
before the return View(meal) in the [HttpPost] method.
exactl...
How to return an array from JNI to Java?
... (JNIEnv *env, jobject jobj){
jobjectArray ret;
int i;
char *message[5]= {"first",
"second",
"third",
"fourth",
"fifth"};
ret= (jobjectArray)env->NewObjectArray(5,
...
Case conventions on element names?
...inent examples:
<a>1</a><b>1</b>
<xsl:value-of select="a+b"/>
outputs 2, as expected
<a>1</a><b>1</b>
<xsl:value-of select="a-b"/>
DOES NOT ERROR, BUT OUTPUTS NOTHING AT ALL
In the above code, you must put at least one space before a su...
How to remove a project (from the workspace) in PHPStorm?
...el.)
1. Click File > Close project
2. From Recent projects, select project, press the fn(on normal keyboard - key between right Alt and Ctrl, not windows key)+Delete
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