大约有 43,000 项符合查询结果(耗时:0.0367秒) [XML]

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MySQL “WITH” clause

... You might be interested in somethinkg like this: select * from ( select * from table ) as Subquery share | improve this answer | follow ...
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XML Schema minOccurs / maxOccurs default values

...ml> <body> <xsl:for-each select="country"> <xsl:value-of select="countryName"/><br/> <xsl:value-of select="capital"/><br/> <xsl:value-of select="nation...
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Python nonlocal statement

...eavily indented when defining inner functions and ends up violating the 79 chars PEP8 recommendation. Any way to get around this problem? Can an inner function somehow be placed outside the outer function? I know the question sounds stupid, but I'm earnest. – tommy.carstensen ...
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Reference alias (calculated in SELECT) in WHERE clause

The calculated value BalanceDue that is set as a variable in the list of selected columns cannot be used in the WHERE clause. ...
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SQL join: selecting the last records in a one-to-many relationship

... want to get a list of all customers along with their last purchase in one SELECT statement. What is the best practice? Any advice on building indexes? ...
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How to parse a query string into a NameValueCollection in .NET

...='); if (parts.Length > 0) { string key = parts[0].Trim(new char[] { '?', ' ' }); string val = parts[1].Trim(); queryParameters.Add(key, val); } } share | improve thi...
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mysql -> insert into tbl (select from another table) and some default values [duplicate]

As the title says, I am trying to insert into one table selecting values from another table and some default values. 5 Ans...
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MySQL ON vs USING?

...n tables ON a column, a set of columns and even a condition. For example: SELECT * FROM world.City JOIN world.Country ON (City.CountryCode = Country.Code) WHERE ... USING is useful when both tables share a column of the exact same name on which they join. In this case, one may say: SELECT ... FR...
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Looping over arrays, printing both index and value

...="snoopy" bar[bar]="nice" bar[baz]="cool" Issue with newlines or special chars Unfortunely, there is at least one condition making this not work anymore: when variable do contain newline: foo[17]=$'There is one\nnewline' Command paste will merge line-by-line, so output will become wrong: past...
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What's faster, SELECT DISTINCT or GROUP BY in MySQL?

...'t, then use DISTINCT. GROUP BY in MySQL sorts results. You can even do: SELECT u.profession FROM users u GROUP BY u.profession DESC and get your professions sorted in DESC order. DISTINCT creates a temporary table and uses it for storing duplicates. GROUP BY does the same, but sortes the disti...