Question

I’m trying to create an Alter command to create an unique_index on the first 8000 characters. I’m not able to figure out how to add the 8000 part. Any help would be appreciated. Thanks!

ALTER TABLE nextractor.tblhtml
  ADD UNIQUE INDEX uniqueindex_InnerHTML (InnerHtml);

Answer 1

According to the MySQL docs, you need something like this:

alter table <table_name> 
  add unique index <index_name> (<column_name> (8000))

---

This is the relevant grammar:

| ADD [CONSTRAINT [symbol]]
        UNIQUE [INDEX|KEY] [index_name]
        [index_type] (index_col_name,...) [index_option] ...

and

index_col_name:
    col_name [(length)] [ASC | DESC]