duda, esta bien la sintaxis alter table?

[BrujoNic]

Primero... si estas usando la BD, NO tenes que referenciarla, o sea, si en algún lado le diste USE ostest, es más que suficiente para que no pongas la BD seguida de la tabla a usar, eso no afecta pero sale sobrando.

Segundo, quitales esas comillas que NO hacen nada.

Las 2 soluciones quedarían así:

Referenciando la BD:
ALTER TABLE ostest.products ADD products_subimage1 VARCHAR(64) AFTER products_bimage
ALTER TABLE ostest.products ADD products_bsubimage1 VARCHAR(64) AFTER products_subimage1
ALTER TABLE ostest.products ADD products_subimage2 VARCHAR(64) AFTER products_bsubimage1
ALTER TABLE ostest.products ADD products_bsubimage2 VARCHAR(64) AFTER products_subimage2
ALTER TABLE ostest.products ADD products_subimage3 VARCHAR(64) AFTER products_bsubimage2
ALTER TABLE ostest.products ADD products_bsubimage3 VARCHAR(64) AFTER products_subimage3
ALTER TABLE ostest.products ADD products_subimage4 VARCHAR(64) AFTER products_bsubimage3
ALTER TABLE ostest.products ADD products_bsubimage4 VARCHAR(64) AFTER products_subimage4
ALTER TABLE ostest.products ADD products_subimage5 VARCHAR(64) AFTER products_bsubimage4
ALTER TABLE ostest.products ADD products_bsubimage5 VARCHAR(64) AFTER products_subimage5
ALTER TABLE ostest.products ADD products_subimage6 VARCHAR(64) AFTER products_bsubimage5
ALTER TABLE ostest.products ADD products_bsubimage6 VARCHAR(64) AFTER products_subimage6

Sin la BD ya que la abriste con USE ostest:
ALTER TABLE products ADD products_subimage1 VARCHAR(64) AFTER products_bimage
ALTER TABLE products ADD products_bsubimage1 VARCHAR(64) AFTER products_subimage1
ALTER TABLE products ADD products_subimage2 VARCHAR(64) AFTER products_bsubimage1
ALTER TABLE products ADD products_bsubimage2 VARCHAR(64) AFTER products_subimage2
ALTER TABLE products ADD products_subimage3 VARCHAR(64) AFTER products_bsubimage2
ALTER TABLE products ADD products_bsubimage3 VARCHAR(64) AFTER products_subimage3
ALTER TABLE products ADD products_subimage4 VARCHAR(64) AFTER products_bsubimage3
ALTER TABLE products ADD products_bsubimage4 VARCHAR(64) AFTER products_subimage4
ALTER TABLE products ADD products_subimage5 VARCHAR(64) AFTER products_bsubimage4
ALTER TABLE products ADD products_bsubimage5 VARCHAR(64) AFTER products_subimage5
ALTER TABLE products ADD products_subimage6 VARCHAR(64) AFTER products_bsubimage5
ALTER TABLE products ADD products_bsubimage6 VARCHAR(64) AFTER products_subimage6