Using Postgresql 9.4
I have a table with a hstore field named 'references' :
Trying to do : select * from table where (references -> 'key' = 'value')
results in
ERROR: syntax error at or near "references"
As it works as expected with another fieldname, I suspect it's because it's a reserved word... but I don't feel like renaming this heavily used field in my application.
So, is there any syntax to work around this problem ?
You need to enclose column names that are keywords in double quotes.
So, thanks to David, the solution is :
select * from table where ( "references"->'key' = 'value' );
where the meaning of quotes and double-quotes is important.
Related
I tried to select a data which is in column "fileName" and its fileName is '2016-11-22-12-55-09_hyun.png'
I tired the
select * from images where 'fileName' like '2016-11-22-12-55-09_hyun.png'
However it can not select anything, nor has any kind of error info.
How can I select this file with its filename? Thank you so much.
Single quotes denote a string literal. So in this query you aren't evaluating the column filename, but checking whether the string 'filename' is like the string '2016-11-22-12-55-09_hyun.png', which it of course is not. Just drop the quotes from filename and you should be OK. Also note that since you aren't using any wildcards, using the like operator is pretty pointless, and you could (should) just a plain old equality check:
select * from images where fileName = '2016-11-22-12-55-09_hyun.png'
-- No quotes -------------^--------^
I have a table with camelCased column names (which I now deeply regret). If I use double quotation marks around the column names as part of the SELECT clause, they work fine, e.g. SELECT "myCamelCasedColumn" FROM the_table;. If, however, I try doing the same in the WHERE clause, then I get an error.
For example, SELECT * FROM the_table WHERE "myCamelCasedColumn" = "hello"; gives me the error column "hello" does not exist.
How can I get around this? If I don't surround the column in double quotation marks then it will just complain that column mycamelcasedcolumn does not exist.
In SQL string literals are enclosed in single quotes, not double quotes.
SELECT *
FROM the_table
WHERE "myCamelCasedColumn" = 'hello';
See the manual for details:
http://www.postgresql.org/docs/current/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS
The manual also explains why "myCamelCasedColumn" is something different in SQL than myCamelCasedColumn
In general you should stay away from quoted identifiers. They are much more trouble than they are worth it. If you never use double quotes everything is a lot easier.
The problem is you use double quote for strin literal "hello". Should be 'hello'. Double quotes is reserved for identifiers.
How do I create a field with a reserved word as the name in MonetDB?
In MySQL I would just surround the field name with backticks, but this doesn't work in MonetDB. What gives?
in MonetDB, double quotes are used for identifiers.
CREATE TABLE test ("year" integer);
I have a question about concat function in PostgreSQL.
This sentence works well in MySQL:
SELECT * FROM words
WHERE CONCAT (word,' ',gender,' ',semantic) LIKE '%"+value+"%'.
Value is a variable that is changed inside my Java program.
But I need the same working in postgresql. How kann I concatenate inside the WHERE clause, using postgres, considering the variable "value" that will have its value changed ?
In Postgresql you concatenate using the following syntax:
(users.first_name || ' ' || users.last_name)
Reference: http://www.postgresql.org/docs/9.1/static/functions-string.html
You can also use this for postgresql:
concat_ws(' ', campo1, campo2) like '%value%'
Note that there is a space between single quotes
I have basic stored procedure that performs a full text search against 3 columns in a table by passing in a #Keyword parameter. It works fine with one word but falls over when I try pass in more than one word. I'm not sure why. The error says:
Syntax error near 'search item' in the full-text search condition 'this is a search item'
SELECT S.[SeriesID],
S.[Name] as 'SeriesName',
P.[PackageID],
P.[Name]
FROM [Series] S
INNER JOIN [PackageSeries] PS ON S.[SeriesID] = PS.[PackageID]
INNER JOIN [Package] P ON PS.[PackageID] = P.[PackageID]
WHERE CONTAINS ((S.[Name],S.[Description], S.[Keywords]),#Keywords)
AND (S.[IsActive] = 1) AND (P.[IsActive] = 1)
ORDER BY [Name] ASC
You will have to do some pre-processing on your #Keyword parameter before passing it into the SQL statement. SQL expects that keyword searches will be separated by boolean logic or surrounded in quotes. So, if you are searching for the phrase, it will have to be in quotes:
SET #Keyword = '"this is a search item"'
If you want to search for all the words then you'll need something like
SET #Keyword = '"this" AND "is" AND "a" AND "search" AND "item"'
For more information, see the T-SQL CONTAINS syntax, looking in particular at the Examples section.
As an additional note, be sure to replace the double-quote character (with a space) so you don't mess up your full-text query. See this question for details on how to do that: SQL Server Full Text Search Escape Characters?
Further to Aaron's answer, provided you are using SQL Server 2016 or greater (130), you could use the in-built string fuctions to pre-process your input string. E.g.
SELECT
#QueryString = ISNULL(STRING_AGG('"' + value + '*"', ' AND '), '""')
FROM
STRING_SPLIT(#Keywords, ' ');
Which will produce a query string you can pass to CONTAINS or FREETEXT that looks like this:
'"this*" AND "is*" AND "a*" AND "search*" AND "item*"'
or, when #Keywords is null:
""