You can run statements like these as you test SELECT (128 & 128) > 7 SELECT (t.bit_flags & 128) > 7 AS myBool FROM myTable t Now the entire number (which, in this case, is 1) is your value. Mask (hide) the seven rightmost bits (using the bitwise operator &), and shift the 8th bit seven spaces to the right, ending up with 00000001. SQL Standard and Multiple Vendor “UPPERCASE” Types.Until MySQL implements a bit datatype, if your processing is truly pressed for space and/or time, such as with high volume transactions, create a TINYINT field called bit_flags for all your boolean variables, and mask and shift the boolean bit you desire in your SQL query.įor instance, if your left-most bit represents your bool field, and the 7 rightmost bits represent nothing, then your bit_flags field will equal 128 (binary 10000000). Reference for the general set of “UPPERCASE” datatypes is below at SQL types that typically expect to be available on at least two backends The “UPPERCASE” datatypes that are part of sqlalchemy.types are common INTEGER, and TIMESTAMP, which inherit directlyįrom the previously mentioned “CamelCase” types
Of UPPERCASE types include VARCHAR, NUMERIC, Of “UPPERCASE” types in a SQLAlchemy application indicates that specificĭatatypes are required, which then implies that the application would normally,īe limited to those backends which use the type exactly as given. Whether or not the current backend supports it. The name of the type is always rendered exactly as given, without regard for Theseĭatatypes are always inherited from a particular “CamelCase” datatype, andĪlways represent an exact datatype. In contrast to the “CamelCase” types are the “UPPERCASE” datatypes. Reference for the general set of “CamelCase” datatypes is below at
MYSQL BOOLEAN FIELD PORTABLE
“CamelCase” types in the general case, as they will generally provide the bestīasic behavior and be automatically portable to all backends. The typical SQLAlchemy application will likely wish to use primarily Interpreting Python numeric or boolean values. As data is sent and receivedįrom the database using this type, based on the dialect in use it may be May render BOOLEAN on a backend such as PostgreSQL, BIT on the Or BIT values 0 and 1, some have boolean literal constants true andįalse while others dont. Not every backend has a real “boolean” datatype some make use of integers Which represents a string datatype that all databases have, If arguments are needed, such as the lengthĪrgument of 60 in the "email_address" column above, the type may beĪnother “CamelCase” datatype that expresses more backend-specific behavior Table definition or in any SQL expression overall, if noĪrguments are required it may be passed as the class itself, that is, without When using a particular TypeEngine class in a
0 kommentar(er)
