You can use CHARINDEX to find a specific character or pattern within a column.CHARINDEX...
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2021-03-09 SQL-Intermediate
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2021-02-24 Introduction to SQL Server
Return a list of unique countries using DISTINCT. Give the results an alias of unique_c...
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2021-02-18 Data Visualization with ggplot2 ch1-4preparation: use library() to load the package and use str() to explore the structure o...
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2021-01-20 Introduction to the Tidyverse Chapter1
How to use filer: must use %>% how to use arrange: Combine filter with arrange: we shou...
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2021-01-18 Datacamp IntermediateR chapter4
Have another look at some useful math functions that R features: abs()[http://www.rdocu...
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2021-01-13 Datacamp R Intermediate Chapter3
As for package:how to load package ( we must know the difference between load and insta...
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2021-01-09 Datacamp-Intermediate R- Chapter2
To consult the documentation on the sample()[http://www.rdocumentation.org/packages/bas...
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2021-01-06 Datacamp-Intermediate R
Write a for loop that iterates over all the elements of linkedin and prints out every e...
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2020-12-18 Datacamp Introduction to R language
用subset()从dataframe里面选中符合条件的数据subset(my_df, subset = some_condition) 排序:order 直接用order...
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SQL ZOO 练习题解法【The JOIN operation】这章主要是多表连接的练习，主要涉及到JOIN的用法：SELECT * FROM game JOIN goal ON (id=matchid)表结构如下 The FROM cl...
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SQL ZOO 练习题解法【SUM and COUNT】
这个板块练习比较少，主要是GROUP BY和 HAVING 的用法。表结构如下： For each continent show the continent and numb...
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SQL ZOO 练习题解法【SELECT from Nobel】
这个版块的练习主要是SELECT的一些查询表结构如下： Show the winners with first name John 注意这里的like，用来查找“John”，...
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SQL ZOO 练习题解法+解析【Select within Select】
【Select within Select】部分题目及解析 表结构如下： #List the name and continent of countries in the c...