定长类型包括
SMALLINT
BOOL
SERIAL
DATE
INT&INTEGER
SMALLFLOAT & REAL
BIGINT
BIGSERIAL
FLOAT&DOUBLE PRECISION
INT8
SERIAL8
DECIMAL、DEC、NUMERIC & MONEY
DATETIME
INTEVAL
CHAR & NCHAR & CHARACTER
变长类型包括
VCHAR
NVCHAR
CHARACTER VARYING
LVCHAR