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Question : Understanding charindex used in t-sql
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Hi,
Only yesterday i asked for some help in a query to enable me to get part of a string out of a field.
I recieved many answers back and this worked the best, however i am relatively new to this and i am finding it difficult to understand the actual working behind the code.
I am hoping someone can explane what is going on here, i was trying to mail this question to the person that wrote this but i can not.
Here is an example of the field i gave:
For example here are two text fields:
Create table customer_history
(history_id int not null,
customer_id int not null,
date_entered datetime not null,
history_text text not null)
Insert into customer_history values (1004963,24829, '2007-06-07 15:48:42.000','BILLING INFO CHANGE
| width=3>| > | TO | bgcolor=#e6e6e6>FROM</tr> d width=3>| Bill Day | 25 > | ;17 </td> | <tr> | Tax Exempt Expiration Date | 06/2007 | > 12/1999
');
Insert into customer_history values (1002583,12345,'2007-06-07 15:48:42.000','BILLING INFO CHANGE
| width=3>| > | TO | bgcolor=#e6e6e6>FROM</tr> d width=3>| Bill Day | 7 | 4 d> | > | Sales Rep | | <td> User, Legacy ble>');
This is the code below:
Declare @SubStringSearch VarChar(200)
Declare @SecondaryStringSearch VarChar(200)
Set @SubStringSearch = 'Bill Day '
Set @SecondaryStringSearch = ' | '
Select history_id,customer_id, date_entered, substring(
substring(history_text,
(charindex(@SubStringSearch,history_text)+ len(@SubStringSearch))
,5)
,0,charindex('&',
substring(history_text,
(charindex(@SubStringSearch,history_text)+ len(@SubStringSearch))
,5))),
substring(substring(
substring(history_text,
(charindex(@SubStringSearch,history_text)+ len(@SubStringSearch))
,Len(cast(history_text as VarChar(max)))
),charindex(@SecondaryStringSearch
, substring(history_text,
(charindex(@SubStringSearch,history_text)+ len(@SubStringSearch))
,Len(cast(history_text as VarChar(max))))) + len(@SecondaryStringSearch),10
),0,
charIndex('&',substring(
substring(history_text,
(charindex(@SubStringSearch,history_text)+ len(@SubStringSearch))
,Len(cast(history_text as VarChar(max)))
),charindex(@SecondaryStringSearch
, substring(history_text,
(charindex(@SubStringSearch,history_text)+ len(@SubStringSearch))
,Len(cast(history_text as VarChar(max))))) + len(@SecondaryStringSearch),10
)))
FROM customer_history
All help greatly appriciated.
Thank you ,
putoch,
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Answer : Understanding charindex used in t-sql
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No there are only 3 parts to a substring -- The Full String, The Starting Position and the Length from the Starting Position.
By adding the ",0" You'll cause a syntax error. If you would like to Check for Null I would Recommend
select IsNull(substring (history_test
(charindex (@SubStringSearch,history_text)+ len(@SubStringSearch))
,5),0)
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