大约有 47,000 项符合查询结果(耗时:0.0272秒) [XML]

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How do you create a read-only user in PostgreSQL?

I'd like to create a user in PostgreSQL that can only do SELECTs from a particular database. In MySQL the command would be: ...
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How to select date from datetime column?

...ry. Use BETWEEN or >, <, = operators which allow to use an index: SELECT * FROM data WHERE datetime BETWEEN '2009-10-20 00:00:00' AND '2009-10-20 23:59:59' Update: the impact on using LIKE instead of operators in an indexed column is high. These are some test results on a table with 1,...
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What is the difference between HAVING and WHERE in SQL?

What is the difference between HAVING and WHERE in an SQL SELECT statement? 20 Answers ...
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How do I find numeric columns in Pandas?

... You could use select_dtypes method of DataFrame. It includes two parameters include and exclude. So isNumeric would look like: numerics = ['int16', 'int32', 'int64', 'float16', 'float32', 'float64'] newdf = df.select_dtypes(include=numer...
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How to save MySQL query output to excel or .txt file? [duplicate]

...SV file: MySQL provides an easy mechanism for writing the results of a select statement into a text file on the server. Using extended options of the INTO OUTFILE nomenclature, it is possible to create a comma separated value (CSV) which can be imported into a spreadsheet application suc...
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Selecting/excluding sets of columns in pandas [duplicate]

...e to create views or dataframes from an existing dataframe based on column selections. 9 Answers ...
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How to get the caret column (not pixels) position in a textarea, in characters, from the start?

...refox, Safari (and other Gecko based browsers) you can easily use textarea.selectionStart, but for IE that doesn't work, so you will have to do something like this: function getCaret(node) { if (node.selectionStart) { return node.selectionStart; } else if (!document.selection) { return ...
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Detect if value is number in MySQL

... This should work in most cases. SELECT * FROM myTable WHERE concat('',col1 * 1) = col1 It doesn't work for non-standard numbers like 1e4 1.2e5 123. (trailing decimal) share ...
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How to get sp_executesql result into a variable?

... DECLARE @ParmDefinition nvarchar(500); DECLARE @tablename nvarchar(50) SELECT @tablename = N'products' SELECT @sSQL = N'SELECT @retvalOUT = MAX(ID) FROM ' + @tablename; SET @ParmDefinition = N'@retvalOUT int OUTPUT'; EXEC sp_executesql @sSQL, @ParmDefinition, @retvalOUT=@retval OUTPUT; SE...
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MySQL: selecting rows where a column is null

I'm having a problem where when I try to select the rows that have a NULL for a certain column, it returns an empty set. However, when I look at the table in phpMyAdmin, it says null for most of the rows. ...