How to Use CAST Function in Analytics

How to Use CAST Function in Analytics
How to Use CAST Function in Analytics

The term CAST came from engineering words. A simple means of this is converting from one data type to another. In Data Science, during analytics, there is an occasion where you need conversion to get data in another data type. Numeric to Char or Char to Varchar. Here, you will know the best example of CAST function usage.

CAST Function Best Data Analytics Examples

Query:1
SELECT timestamp_column, 
CAST(timestamp_column 
AS varchar(10)) 
FROM date_time_types; 
Query:2
SELECT timestamp_column::varchar(10) 
FROM date_time_types; 
Query:3
SELECT numeric_column,
         CAST(numeric_column AS integer),
         CAST(numeric_column AS varchar(6))
FROM number_data_types;
Query:4
SELECT CAST(char_column AS integer) 
FROM char_data_types;

Explanation on the Usage

Here, double colon refers to CAST function. It is a shortcut to the CAST function.

Query:1 

The Varchar (10) gets only the first 10 bytes of data from Timestamp. In reality, you have other functions to get Time from Timestamp. It is also one method you can use.

Query:2 

The double-colon works the same as the CAST function. You will get Time from the Timestamp.

Query:3  

It writes numeric-column three times – original value, Integer, and Varchar of length 6.

Query: 4 

It fails and writes an error since you cannot convert CHAR to numeric.

Takeaways

  1. Always check target datatype length before you use CAST
  2. You cannot convert CHAR to numeric value.

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Author: Srini

Experienced software developer. Skills in Development, Coding, Testing and Debugging. Good Data analytic skills (Data Warehousing and BI). Also skills in Mainframe.