SQL Statement indentation good practice

What is the accepted practice for indenting SQL statements? For example, consider the following SQL statement:

SELECT column1, column2
FROM table1
WHERE column3 IN
(
SELECT TOP(1) column4
FROM table2
INNER JOIN table3
ON table2.column1 = table3.column1
)

How should this be indented? Many thanks.

SELECT column1
     , column2
FROM table1
WHERE column3 IN
(
	SELECT TOP(1) column4
	FROM table2
	INNER JOIN table3
	ON table2.column1 = table3.column1
)

I like to have all "," in front, this way I never search them when an error at line X from the SQL editor.

---

###This is an example for those who do not use this type of writting SQL statement. Both contain an error of a missing comma.

SELECT sdcolumn123
 , dscolumn234
 , sdcolumn343
 , ffcolumn434
 , sdcolumn543
 , bvcolumn645
  vccolumn754
 , cccolumn834
 , vvcolumn954
 , cvcolumn104
FROM table1
WHERE column3 IN
(
	...
)

SELECT sdcolumn123, dscolumn234, asdcolumn345, dscolumn456, ascolumn554, gfcolumn645 sdcolumn754, fdcolumn845, sdcolumn954, fdcolumn1054
FROM table1
WHERE column3 IN
(
	...
)

I found easier and more quick at the first example. Hope this example show you more my point of view.

SELECT column1, column2
FROM table
WHERE column3 IN (
    SELECT TOP(1) column4
    FROM table2
    INNER JOIN table3 ON table2.column1 = table3.column1
)

This is pretty short and easy to read. I'd make adjustments if there were more columns selected or more join conditions.

Not sure there is an accepted practice, but here's now how I'd do it:

SELECT 
    column1, 
    column2 
FROM 
    table1 
WHERE 
    column3 IN 
    ( 
     SELECT TOP(1) 
         column4 
     FROM 
         table2 
         INNER JOIN 
         table3 
             ON table2.column1 = table3.column1 
    )

I like to have "rivers" of white space in the code. It makes it a little easier to scan.

SELECT column1,
       column2
  FROM table1
 WHERE column3 IN (SELECT column4
                     FROM table2
                     JOIN table3
                       ON table2.column1 = table3.column1);

I like jalbert's form of lining up the keywords on their right. I'd also add that I like the ANDs and ORs on the left (some people put them on the right.) In addition, I like to line up my equals signs when possible.

SELECT column1,
column2

FROM table1, table2
WHERE table1.column1 = table2.column4
AND table1.col5    = "hi"
OR table2.myfield = 678

This is my personal method. Depending on the length of the join condition I sometimes indent it on the line below.

SELECT
  column1,
  column2
FROM
  table1
WHERE
  column3 IN ( 
    SELECT TOP(1)
      column4
    FROM
      table2
      INNER JOIN table3 ON table2.column1 = table3.column1
  )


SELECT
  column1,
  column2
FROM
  table1
WHERE
  column3 IN ( 
    SELECT TOP(1)
      column4
    FROM
      table2
      INNER JOIN table3
        ON table2.column1 = table3.column1 -- for long ones
  )

I've written a code standard for our shop that is biased in the extreme towards readability/"discoverability" (the latter being primarily useful in insert-select statements):

SELECT 
    column1, 
    column2
FROM 
    table1
WHERE 
    column3 IN
    (
        SELECT TOP(1) 
            column4
        FROM 
            table2
            INNER JOIN table3 ON table2.column1 = table3.column1
    )

On more complex queries it becomes more obvious how this is useful:

SELECT
    Column1,
    Column2,
    Function1
    (
        Column1,
        Column2
    ) as Function1,
    CASE
    WHEN Column1 = 1 THEN
        a
    ELSE
        B
    END as Case1       
FROM
    Table1 t1
    INNER JOIN Table2 t2 ON t1.column12 = t2.column21
WHERE
    (
        FilterClause1
        AND FilterClause2
    )
    OR
    (
        FilterClause3
        AND FilterClause4
    )

Once you move to systems with more than a single join in most of your queries, it has been my experience that using vertical space liberally is your best friend with complex SQL.

SQL formatting is an area where there is a great deal of variance and disagreement... But fwiw, I like to focus on readability and think that whatever you do, consistently conforming to any rules that reduce readability is, as the old cliche goes, a "foolish consistency" ( "Foolish consistency is a hobgoblin for simple minds" )

So, instead of calling them rules, here are some guidelines. For each Major clause in a SQL statement (Select, Insert, Delete, From, Where, Having, Group BY, Order By, ... I may be missing a few) should be EASILY identifiable. So I generally indent them at the highest level, all even with each other. Then within each clause, I indent the next logical sub structure evenly... and so on.. But I feel free to (and often do) change the pattern if in any individual case it would be more readable to do so... Complex Case statements are a good example. Because anything that requires horizontal scrolling reduces readability enormously, I often write complex (nested) Case expressions on multiple lines. When I do, I try to keep the beginning of such a statement hanging indent based on it's logical place in the SQL statement, and indent the rest of the statement lines a few characters furthur...

SQL Database code has been around for a long time, since before computers had lower case, so there is a historical preference for upper casing keywords, but I prefer readability over tradition... (and every tool I use color codes the key words now anyway)

I also would use Table aliases to reduce the amount of text the eye has to scan in order to grok the structure of the query, as long as the aliases do not create confusion. In a query with less than 3 or 4 tables, Single character aliases are fine, I often use first letter of the table if all ther tables start with a different letter... again, whatever most contributes to readability. Finally, if your database supports it, many of the keywords are optional, (like "Inner", "Outer", "As" for aliases, etc.) "Into" (from Insert Into) is optional on Sql Server - but not on Oracle) So be careful about using this if your code needs to be platform independant...

Your example, I would write as:

Select column1, column2
From table1 T1
Where column3 In (Select Top(1) column4
                  From table2 T2
                     Join table3 T3
                         On T2.column1 = T3.column1)

Or

Select column1, column2
From table1 T1
Where column3 In 
     (Select Top(1) column4
      From table2 T2
         Join table3 T3
            On T2.column1 = T3.column1)

If there many more columns on the select clause, I would indent the second and subsequent lines... I generally do NOT adhere to any strict (one column per row) kind of rule as scrolling veritcally is almost as bad for readability as scrolling horizontally is, especially if only the first ten columns of the screen have any text in them)

Select column1, column2, Col3, Col4, column5,
    column6, Column7, isNull(Column8, 'FedEx') Shipper,
    Case Upper(Column9) 
       When 'EAST'  Then 'JFK'
       When 'SOUTH' Then 'ATL'
       When 'WEST'  Then 'LAX'
       When 'NORTH' Then 'CHI' End HubPoint
From table1 T1
Where column3 In 
     (Select Top(1) column4
      From table2 T2
         Join table3 T3
            On T2.column1 = T3.column1)

Format the code in whatever manner makes it the most readable...

If you have a lengthy SQL statement that you'd like to reformat without all the typing and tabbing, you can slap it into this website and get a nicely formatted result. You can experiment with various formats to see which makes your text the most readable.

Edit: I believe that this is the 2014 location of the SQL formatter.

I like to have the different parts of my query line up vertically. I tend to use a tab size of 8 spaces for SQL which seems to work well.

SELECT  column1, 
        column2
FROM    table1
WHERE   column3 IN
(
        SELECT TOP(1) column4
        FROM    table2
        INNER JOIN table3
        ON      table2.column1  = table3.column1
)

Example indenting a very very very complex SQL:

SELECT 
	produtos_cesta.cod_produtos_cesta, 
	produtos.nome_pequeno,
	tab_contagem.cont,
	produtos_cesta.sku, 
	produtos_kits.sku_r AS sku_kit, 
	sku_final = CASE
		WHEN produtos_kits.sku_r IS NOT NULL THEN produtos_kits.sku_r
		ELSE produtos_cesta.sku
	END,
	estoque = CASE
		WHEN produtos2.estoque IS NOT NULL THEN produtos2.estoque
		ELSE produtos.estoque
	END,
	produtos_cesta.unidades as unidades1, 
	unidades_x_quantidade = CASE
		WHEN produtos.cod_produtos_kits_tipo = 1 THEN CAST(produtos_cesta.quantidade * (produtos_cesta.unidades / tab_contagem.cont) * produtos_kits.quantidade AS int)
		ELSE CAST(produtos_cesta.quantidade * produtos_cesta.unidades AS int)
	END,
	unidades = CASE
		WHEN produtos.cod_produtos_kits_tipo = 1 THEN produtos_cesta.unidades / tab_contagem.cont * produtos_kits.quantidade
		ELSE produtos_cesta.unidades
	END,
	unidades_parent = produtos_cesta.unidades,
	produtos_cesta.quantidade,
	produtos.controla_estoque, 
	produtos.status
FROM 
	produtos_cesta 
INNER JOIN produtos 
	ON (produtos_cesta.sku = produtos.sku) 
INNER JOIN produtos_pacotes 
	ON (produtos_cesta.sku = produtos_pacotes.sku) 
INNER JOIN (
	SELECT 
		produtos_cesta.cod_produtos_cesta,
		cont = SUM(
			CASE
				WHEN produtos_kits.quantidade IS NOT NULL THEN produtos_kits.quantidade
				ELSE 1
			END
		)
	FROM 
		produtos_cesta 
	LEFT JOIN produtos_kits 
		ON (produtos_cesta.sku = produtos_kits.sku) 
	LEFT JOIN produtos 
		ON (produtos_cesta.sku = produtos.sku) 
	WHERE 
		shopper_id = '" + mscsShopperId + @"' 
	GROUP BY 
		produtos_cesta.cod_produtos_cesta, 
		produtos_cesta.sku, 
		produtos_cesta.unidades 
) 
AS tab_contagem
	ON (produtos_cesta.cod_produtos_cesta = tab_contagem.cod_produtos_cesta)
LEFT JOIN produtos_kits 
	ON (produtos.sku = produtos_kits.sku) 
LEFT JOIN produtos as produtos2
	ON (produtos_kits.sku_r = produtos2.sku) 
WHERE 
	shopper_id = '" + mscsShopperId + @"' 
GROUP BY 
	produtos_cesta.cod_produtos_cesta, 
	tab_contagem.cont,
	produtos_cesta.sku, 
	produtos_kits.sku_r, 
	produtos.cod_produtos_kits_tipo, 
	produtos2.estoque,
	produtos.controla_estoque, 
	produtos.estoque, 
	produtos.status, 
	produtos.nome_pequeno, 
	produtos_cesta.unidades, 
	produtos_cesta.quantidade,
	produtos_kits.quantidade
ORDER BY 
	produtos_cesta.sku, 
	produtos_cesta.unidades DESC

As most above have lined up the return column names, I find lining up tables names and conditions helps readability a lot.

SELECT 
    column1, 
    column2
FROM 
    table1
WHERE 
    column3 IN
    (
        SELECT TOP(1) 
            column4
        FROM 
            table2 INNER JOIN 
            table3 ON table2.column1 = table3.column1
    )

And for when join conditions get long.

SELECT
    Column1,
    Column2
FROM 
    Table1 JOIN 
    Table2 ON 
        Table1.Column3 = Table2.Column4 JOIN 
    Table3 ON 
        Table2.Column1 = Table3.Column1 and
        Table2.ColumnX = @x and
        Table3.ColumnY = @y
WHERE
    Condition1=xxx and
    Condition2=yyy and
    (
        Condition3=aaa or
        Condition4=bbb
    )

Here's my poke at this:

select column1, column2
    from table1
    where (column3 in (
        select top(1) column4
            from table2
            inner join table3
                on (table2.column1 = table3.column1)
    ))
;

• Everything lowercase because it's easier to read lowercase characters (and we have code highlighting to emphasize keywords) also easier to type
• Every restriction or option on a keyword (like the from on the select or the on on the join) is indented to show their dependance on the outward keyword
• The closing bracket is at the same indenting level as the opening where
• Use brackets for where- and on-clauses to increase readability
• Have the semicolon closing the select-statement at the same indenting so multiple statements can be distinguished better (if you need a semicolon in your language like SAS PROC SQL does)
• It's still quite compact and does not stretch all over the page

Of course, this comes down to personal preference. And if in a team setting, it's something that should be agreed upon among the members for consistency's sake. But this would be my preference:

SELECT column1, column2
FROM   table1
WHERE  column3 IN(SELECT     TOP(1) column4
                  FROM       table2
                  INNER JOIN table3 ON
                             table2.column1 = table3.column1
                 )

I would format like this:

SELECT
    column1, 
    column2
FROM 
    table1
WHERE 
    column3 IN (SELECT TOP(1) 
                    column4 
                FROM 
                    table2 
                    INNER JOIN table3 ON table2.column1 = table3.column1)

or like this:

SELECT
    column1, 
    column2
FROM 
    table1
WHERE 
    column3 IN (SELECT TOP(1) column4 
                FROM table2 
                INNER JOIN table3 ON table2.column1 = table3.column1)

This is my normal preference:

    SELECT column1
        ,column2
    FROM table1
    WHERE column3 IN (
        SELECT TOP(1) column4
        FROM table2
        INNER JOIN table3
            ON table2.column1 = table3.column1
    )

Well, of course it depends on the query.

For simple queries, a highly formal indentation scheme is just more trouble than it's worth and can actually make the code less readable, not more. But as complexity grows you need to start being more careful with how you structure the statement, to make sure it will be readable again later.

Yeah, this is pretty subjective...But here's my 2 cents:

SELECT
   Column1,
   Column2
FROM Table1
WHERE 
   Column3 IN (
      SELECT Column4
      FROM Table2
      JOIN Table3 ON
         Table2.Column1 = Table3.Column1
   )

But, really, I'd probably rewrite it without the IN:

SELECT
   Column1,
   Column2
FROM Table1
JOIN Table2 ON
   Table1.Column3 = Table2.Column4
JOIN Table3 ON
   Table2.Column1 = Table3.Column1

Basically, my rules are:

• Capitalize Keywords
• Columns go on individual lines, but SELECT modifiers (SELECT TOP 100, SELECT DISTINCT, etc.) or single columns (SELECT 1, SELECT Id, SELECT *, etc.) go on same line
• Join conditions indented underneath JOIN clause
• Use JOIN for INNER JOIN (since it's the common one), and fully specify others (LEFT OUTER JOIN, FULL OUTER JOIN, etc.)
• Open parens on same line, close paren on separate line. If you have an alias, the alias goes with close paren.

I've just put it through my SQL prettifier and it came out like this....

SELECT column1, column2
FROM table1
WHERE column3 IN
(
SELECT TOP(1) column4
    FROM table2
            INNER JOIN table3
            ON table2.column1 = table3.column1
)

http://extras.sqlservercentral.com/prettifier/prettifier.aspx

.....But I haven't worked out a way of getting colours into StackOverflow.

I don't know if there's a standard but I like to do it this way;

SELECT column1, column2
  FROM table1
WHERE column3 IN
(
    SELECT TOP(1) column4
      FROM table2
    INNER JOIN table3
      ON table2.column1 = table3.column1
)

because I can read and analyze the SQL better.

SELECT
    Column1,
    Column2
FROM
    Table1
WHERE
    Column3 IN
    (
        SELECT TOP (1)
            Column4
        FROM 
            Table2
        INNER JOIN 
            Table3
        ON
            Table2.Column1 = Table3.Column1
    )

What I usually do is,

print("SELECT column1, column2
       FROM table1
       WHERE column3 IN (SELECT TOP(1) column4
                         FROM table2 INNER JOIN 
                              table3 ON table2.column1 = table3.column1)");

This is a matter of taste.

This is my preference.

SELECT 
  column1
 ,column2
FROM
  table1
WHERE column3 IN (
                 SELECT TOP(1) column4
                 FROM 
                   table2
                   INNER JOIN table3
                 ON table2.column1 = table3.column1
                 )

That's how we would do it here:

select
COLUMN1,
COLUMN2,
case    when    COLUMN5 = 'X'
and
COLUMN6 = 'Y'
then    'one'
when    COLUMN5 in (
'AAA',
'BBB'
)
then    'two'
else    'three'
end as COLUMN7
from
TABLE1
where
COLUMN2 in (
select top(1)
COLUMN4
from
TABLE2
inner join
TABLE3
on
TABLE2.COLUMN1 = TABLE3.COLUMN1
and
TABLE2.COLUMN2
between
TABLE3.COLUMN2
and
TABLE3.COLUMN3
)

Our idea is: keep sql keywords in lower case and put all changing (and therefore "more interesting") things like table or column names in upper case. The code might look a bit "blown up" here, but it increases readability if you have complex queries with longer names (incl. schema etc.) much longer than in this example. And: indent all objects according to their "level".