Sfrgttk

How can guns be countered by melee combat without raw-ability or exceptional explanations?

Do all Half-Elf subraces forgo the Skill Versatility feature?

Short Story - Man lives in isolation in a compound, plays tennis against a robot, arranges meeting with a woman

find command cannot find my files which do exist

Do error bars on probabilities have any meaning?

Misplaced noalign when centering tabularx cell

Getting size of dynamic C-style array vs. use of delete[]. Contradiction?

How does the income of your target audience matter for logo design?

Is Apex Sometimes Case Sensitive?

Truncating the output of AES-128

Could Comets or Meteors be used to Combat Global Warming?

Is my plan for an air admittance valve ok?

Buying a "Used" Router

Build ASCII Podiums

Are encryption algorithms with fixed-point free permutations inherently flawed?

Rudeness by being polite

Why is ra lower than re while la is higher than le?

How do I handle a blinded enemy which wants to attack someone it's sure is there?

How do I write a maintainable, fast, compile-time bit-mask in C++?

Determining whether a system is consistent or inconsistent from the linear dependence of its columns

1730 House how to make Ceiling Level

Why is Bernie Sanders maximum accepted donation on actblue $5600?

How to play songs that contain one guitar when we have two or more guitarists?

Microphone on Mars

Explain an OVER clause

0

I saw a concise TSQL statement that effectively splits a string into its constituent characters, one per line, for the purpose of evaluating the ascii value on each character.

If I am reading the query correctly, effectively, 3 CTEs are being used to prepare a table of 1 column containing 10,000 rows, each with the value '0'.

A fourth CTE is defined as follows:

cteTally(n) AS(

    SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) n 

    FROM E4

)

Subsequently, this CTE is joined to a table containing a column with the strings of interest, with the following select:

SELECT n, SUBSTRING(LastName, n, 1), ASCII( SUBSTRING(LastName, n, 1))

That is, row number n, then the nth character in LastName, then the ascii value of that character.

My questions relate to the over clause in the CTE above.

Essentially, what exactly is it doing?

If we are querying row_number from 10,000 identical rows, why do we need an order by clause at all? Why is the order by put into an over clause rather than as an order by clause for the select statement - especially as the over clause isn't even specifying any partition? (I presume this means the window over which row_number operates is the full 10,000 rows?) And what does it mean to order by select null?

sql-server t-sql window-functions

share

asked 36 secs ago

youcantryreachingmeyoucantryreachingme

2817

add a comment | 

0

I saw a concise TSQL statement that effectively splits a string into its constituent characters, one per line, for the purpose of evaluating the ascii value on each character.

If I am reading the query correctly, effectively, 3 CTEs are being used to prepare a table of 1 column containing 10,000 rows, each with the value '0'.

A fourth CTE is defined as follows:

cteTally(n) AS(

    SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) n 

    FROM E4

)

Subsequently, this CTE is joined to a table containing a column with the strings of interest, with the following select:

SELECT n, SUBSTRING(LastName, n, 1), ASCII( SUBSTRING(LastName, n, 1))

That is, row number n, then the nth character in LastName, then the ascii value of that character.

My questions relate to the over clause in the CTE above.

Essentially, what exactly is it doing?

If we are querying row_number from 10,000 identical rows, why do we need an order by clause at all? Why is the order by put into an over clause rather than as an order by clause for the select statement - especially as the over clause isn't even specifying any partition? (I presume this means the window over which row_number operates is the full 10,000 rows?) And what does it mean to order by select null?

sql-server t-sql window-functions

share

asked 36 secs ago

youcantryreachingmeyoucantryreachingme

2817

add a comment | 

I saw a concise TSQL statement that effectively splits a string into its constituent characters, one per line, for the purpose of evaluating the ascii value on each character.

If I am reading the query correctly, effectively, 3 CTEs are being used to prepare a table of 1 column containing 10,000 rows, each with the value '0'.

A fourth CTE is defined as follows:

cteTally(n) AS(

    SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) n 

    FROM E4

)

Subsequently, this CTE is joined to a table containing a column with the strings of interest, with the following select:

SELECT n, SUBSTRING(LastName, n, 1), ASCII( SUBSTRING(LastName, n, 1))

That is, row number n, then the nth character in LastName, then the ascii value of that character.

My questions relate to the over clause in the CTE above.

Essentially, what exactly is it doing?

If we are querying row_number from 10,000 identical rows, why do we need an order by clause at all? Why is the order by put into an over clause rather than as an order by clause for the select statement - especially as the over clause isn't even specifying any partition? (I presume this means the window over which row_number operates is the full 10,000 rows?) And what does it mean to order by select null?

sql-server t-sql window-functions

share

asked 36 secs ago

youcantryreachingmeyoucantryreachingme

2817

cteTally(n) AS(

    SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) n 

    FROM E4

)

SELECT n, SUBSTRING(LastName, n, 1), ASCII( SUBSTRING(LastName, n, 1))

share

asked 36 secs ago

youcantryreachingmeyoucantryreachingme

2817

share

asked 36 secs ago

youcantryreachingmeyoucantryreachingme

2817

asked 36 secs ago

youcantryreachingmeyoucantryreachingme

2817

asked 36 secs ago

youcantryreachingmeyoucantryreachingme

2817