Abstract the support for ORDER BY and LIMIT/OFFSET SQL generation
all DB engines do not support the same syntax for these features, MS SQLServer being the bad boy we try to support in CW.
* Use two new methods of dbhelper to add LIMIT/OFFSET clauses and ORDER BY clauses
* added unit tests for sqlserver backend
* changed unittest_rql2sql to lauch the backend tests even if the driver module is not installed on the machine, so
that we can run the sqlserver tests on linux (and the mysql tests too)
* adapt msstep.py to the new interface
closes #1154756
def migrate_varchar_to_nvarchar():
dbdriver = config.sources()['system']['db-driver']
if dbdriver != "sqlserver2005":
return
introspection_sql = """\
SELECT table_schema, table_name, column_name, is_nullable, character_maximum_length
FROM information_schema.columns
WHERE data_type = 'VARCHAR' and table_name <> 'SYSDIAGRAMS'
"""
has_index_sql = """\
SELECT i.name AS index_name,
i.type_desc,
i.is_unique,
i.is_unique_constraint
FROM sys.indexes AS i, sys.index_columns as j, sys.columns as k
WHERE is_hypothetical = 0 AND i.index_id <> 0
AND i.object_id = j.object_id
AND i.index_id = j.index_id
AND i.object_id = OBJECT_ID('%(table)s')
AND k.name = '%(col)s'
AND k.object_id=i.object_id
AND j.column_id = k.column_id;"""
generated_statements = []
for schema, table, column, is_nullable, length in sql(introspection_sql, ask_confirm=False):
qualified_table = '[%s].[%s]' % (schema, table)
rset = sql(has_index_sql % {'table': qualified_table, 'col':column},
ask_confirm = False)
drops = []
creates = []
for idx_name, idx_type, idx_unique, is_unique_constraint in rset:
if is_unique_constraint:
drops.append('ALTER TABLE %s DROP CONSTRAINT %s' % (qualified_table, idx_name))
creates.append('ALTER TABLE %s ADD CONSTRAINT %s UNIQUE (%s)' % (qualified_table, idx_name, column))
else:
drops.append('DROP INDEX %s ON %s' % (idx_name, qualified_table))
if idx_unique:
unique = 'UNIQUE'
else:
unique = ''
creates.append('CREATE %s %s INDEX %s ON %s(%s)' % (unique, idx_type, idx_name, qualified_table, column))
if length == -1:
length = 'max'
if is_nullable == 'YES':
not_null = 'NULL'
else:
not_null = 'NOT NULL'
alter_sql = 'ALTER TABLE %s ALTER COLUMN %s NVARCHAR(%s) %s' % (qualified_table, column, length, not_null)
generated_statements+= drops + [alter_sql] + creates
for statement in generated_statements:
print statement
sql(statement, ask_confirm=False)
commit()
migrate_varchar_to_nvarchar()