英文:
KQL: How to get max(strlen(colname)) for all (string type) columns in general?
问题
我有一个包含各种字符串类型列的表。我想要一个以（列名 | 最大列长度）形式的“摘要”。
我看到getschema函数可以获取带有类型的列，但我不知道如何利用它来获取最大列长度，而不是明确引用每个列。我正在寻找一种通用的（查询中没有明确名称）方法来实现这一点，它将针对运行的任何表都能正常工作。
在SQL中，我会认为这是一个动态SQL用例。
在Kusto Query Language (KQL) 中应该如何做呢？
英文:
I have a table with various string type columns. I want a "summary" of the form (colname | maxcollength).
I see the getschema function gets me the columns with types, but I have no idea how to leverage that to pull maxcollength without explicitly referencing each column. I'm looking for a general (no explicit names in the query) way to achieve this, which will work OOB against any table it runs against.
In sql I would think of this as a dynamic sql use case.
How would one do it in kql?
答案1
得分: 1
以下是翻译好的部分：
你可以运行此查询以生成一个会产生所需结果的查询：
let TableName = "MyTable";
let TimeFilter = "where Timestamp > ago(1d)";
table(TableName)
| getschema
| where ColumnType == "string"
| summarize Temp = array_strcat(make_list(strcat("max(strlen(", ColumnName, "))")), ", ")
| project strcat(TableName, " | ", TimeFilter, " | summarize ", Temp)
只需更新前两行，设置表名和所需的时间筛选条件。
结果将是这样的查询：
MyTable
| where LastUpdated > ago(1d)
| summarize max(strlen(MyStringColumn)), max(strlen(AnotherStringColumn)), ...
这正是你需要运行以获得所需结果的查询。
英文:
You can run this query to generate a query that will produce the results you need:
let TableName = "MyTable";
let TimeFilter = "where Timestamp > ago(1d)";
table(TableName)
| getschema
| where ColumnType == "string"
| summarize Temp = array_strcat(make_list(strcat("max(strlen(", ColumnName, "))")), ", ")
| project strcat(TableName, " | ", TimeFilter, " | summarize ", Temp)
Just update the first two lines, where you set the table name, and the desired time filter.
As a result, you'll get a query that looks like this:
MyTable
| where LastUpdated > ago(1d)
| summarize max(strlen(MyStringColumn)), max(strlen(AnotherStringColumn)), ...
This is exactly the query you need to run to get the desired result.
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