Sql notes

From raju

convert date to YYYYMMDD form

select fld1, convert(varchar(10), fld_date, 112) fld_date, fld3, fld4
from table 
where fld1 in ('valA' ,'valB')

convert date to YYYY-MM-DD

To convert a date to iso string in sybase ase

    select str_replace( convert( varchar, ColumnName, 111), '/', '-') NewColumnName
    

tag | convert date to iso string

split a string

Situation:
One column in a sql table is of the form

    field1|field2|field3|...|fieldN
    

Task:
Split this into two columns - every thing but the last field, last field.

Solution:

    select substring(col_name, 1, len(col_name)-charindex('|', reverse(col_name))) all_but_last_field,
           substring(col_name, len(col_name)-charindex('|', reverse(col_name))+2, len(col_name)) last_field,
           *
      from table_name
    

Explanation:

  • The length of the string, N, is given by len(col_name).
  • The range of charindex is [1:N].
  • If P is the position of the last delimiter when counted from end, its position would be N-P+1 when counted from the beginning.
  • So, the fields that we want are [1:N-P],[N-P+2:N]
  • P is given by charindex('|', reverse(col_name))

tags | split string sybase sql table, split a string and get the last field

Ref:- http://stackoverflow.com/questions/14412898/split-string-and-take-last-element

get most recent record

Say we have a table with three fields - cusip, as_of and quantity. New entries are added if and only if the quantity of a cusip changes from previous day. The task is to find the most recent quantity for a given date and a list of cusips.

Assume the list of cusips is given as "000324AA1","000361AH8", "00103YAE1","00130HBH7"

Assume the date of interest is '20160701'

The query would be something like

    select a.cusip, convert(varchar(8), a.as_of, 112) as 'date', a.quantity
    from tbl a
    inner join (
        select cusip, max(as_of) as as_of
        from tbl
        where cusip in ("000324AA1","000361AH8", "00103YAE1","00130HBH7")
        and convert(varchar(8), as_of, 112) <= '20160701'
        group by cusip
        ) b
        on a.cusip=b.cusip and a.as_of = b.as_of
    go
    

tags | query the latest record

Ref:- http://stackoverflow.com/questions/8523374/mysql-get-most-recent-record

enclose each line in quotes

Use case 1:

    head -n1 foo.csv | tr ',' '\n' | sed 's/\(.*\)/"\1"/g'
    

For example

    % echo "foo1,foo2,bar1,bar2" | tr ',' '\n' | sed 's/\(.*\)/\tstructField("\1", ""),/g'
            structField("foo1", ""),
            structField("foo2", ""),
            structField("bar1", ""),
            structField("bar2", ""),
    

Use case 2:

    % cat ~/bin/sqlin
    sed 's/\(.*\)/"\1"/g' | tr '\n' ',' | sed -e 's/^/(/g' -e 's/,$/)\n/g'
    
    % chmod +x ~/bin/sqlin
    

Sample input:

    % cat foo.txt
    cusip
    06739FHV6
    655844AJ7
    06738C828
    61747YCM5
    084664CE9
    

Sample usage:

    % cat ~/x/foo.txt | tail -n +2 | ~/bin/sqlin
    ("06739FHV6","655844AJ7","06738C828","61747YCM5","084664CE9")
    

tags | quote string for sql in clause

remove extra spaces at the end

    SELECT RTRIM(column)
    

stackoverflow links

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