fix sql templates

[Medienkunzt]

Currently, several templates in our playground use CHAR(50) as a datatype. Unfortunately, this datatype fills empty characters with whitespace. As a result, queries such as attr LIKE 'D%d' yield no results, even though there are entries with 'Dortmund'. This occurs because the LIKE operator considers the trailing spaces as part of the string.

To address this issue, we need to change all instances of CHAR(xx) to VARCHAR(xx) in our database templates. The VARCHAR datatype does not pad strings with trailing spaces, which will resolve the issue with the LIKE operator.

Additionally, we have identified cases where inserted data has trailing spaces, such as "Berlin ". These instances need to be cleaned up by trimming the trailing spaces from the affected data.

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