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Diffstat (limited to 'doc/build/sqlexpression.rst')
| -rw-r--r-- | doc/build/sqlexpression.rst | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/doc/build/sqlexpression.rst b/doc/build/sqlexpression.rst index c34e6e790..0870bc848 100644 --- a/doc/build/sqlexpression.rst +++ b/doc/build/sqlexpression.rst @@ -84,11 +84,34 @@ Next, to tell the ``MetaData`` we'd actually like to create our selection of tab () COMMIT -Users familiar with the syntax of CREATE TABLE may notice that the VARCHAR columns were generated without a length; on SQLite, this is a valid datatype, but on most databases it's not allowed. So if running this tutorial on a database such as PostgreSQL or MySQL, and you wish to use SQLAlchemy to generate the tables, a "length" may be provided to the ``String`` type as below:: - - Column('name', String(50)) - -The length field on ``String``, as well as similar fields available on ``Integer``, ``Numeric``, etc. are not referenced by SQLAlchemy other than when creating tables. +.. note:: Users familiar with the syntax of CREATE TABLE may notice that the + VARCHAR columns were generated without a length; on SQLite and Postgresql, + this is a valid datatype, but on others, it's not allowed. So if running + this tutorial on one of those databases, and you wish to use SQLAlchemy to + issue CREATE TABLE, a "length" may be provided to the ``String`` type as + below:: + + Column('name', String(50)) + + The length field on ``String``, as well as similar precision/scale fields + available on ``Integer``, ``Numeric``, etc. are not referenced by + SQLAlchemy other than when creating tables. + + Additionally, Firebird and Oracle require sequences to generate new + primary key identifiers, and SQLAlchemy doesn't generate or assume these + without being instructed. For that, you use the ``Sequence`` construct:: + + from sqlalchemy import Sequence + Column('id', Integer, Sequence('user_id_seq'), primary_key=True) + + A full, foolproof ``Table`` is therefore:: + + users_table = Table('users', metadata, + Column('id', Integer, Sequence('user_id_seq'), primary_key=True), + Column('name', String(50)), + Column('fullname', String(50)), + Column('password', String(12)) + ) Insert Expressions ================== |