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Tag: column name

How to use aggregates with list names

How do I summarize the aggregation in a function by passing a list of conditions and values?

# This works fine:
x <- data.frame(cond1 = sample(letters[1:3], 500, replace=TRUE) , cond2 = sam

September 30, 2021By Simo Design Pattern aggregate, column name, How to, List, TogetherLeave a Comment

When I don’t want to use aggregate, I should use Pivot to convert SQL Server 2008 row value to column names?

I am trying to master the manipulation of table data into a more visually attractive output format. This may be part of the problem, because what I want may be for a separate reporting software. <

September 30, 2021By Simo Design Pattern aggregate, column name, conversion, Do not want, Pivot, Row, server, SQL, time, use, value, whether it shouldLeave a Comment

How to use custom column names (using “by”) Data.Table without using “: =”?

I know I can do this

a <- dt[,sum(x), by=y ] I can do this too

dt[,z:=sum(x), by=y] # this would modify dt But I don’t know why I can’t do this:

a <- dt[,z=sum(x), by=y] < p>How t

September 30, 2021By Simo Design Pattern aggregate, column name, customize, data, Data.Table, how to use, table, useLeave a Comment

PowerDesigner table name, column name size write conversion

From Open Source China: https://my.oschina.net/chwencong/blog/52650 PowerDesigner table name, column name case conversion Collection Car water code farmers Posted in 5

September 22, 2021By Simo Power Designer column name, conversion, Name, PowerDesigner, table, uppercaseLeave a Comment

SQLite – How to get the primary key column name for a given table?

All I know is the name of the table and the id value of the query I want to execute, but I don’t know what id is called in the table. You can use the answer to a quite similar question to find t

September 22, 2021By Simo Sqlite column name, given, how to get, key, master, SQLITE, tableLeave a Comment
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