The column name must be made up of alphanumeric characters. If the column name includes any other characters, it must be enclosed with double quotation marks. Managed Services. Talent Sourcing. Business Solutions Consulting Training. Resource Center. We'd better to check the definition by describing the table.
This pattern is rare though, we should talk about non-existent function calls. Let's see how we reproduce ORA The third case is to select a misspelled and false column name, which is the most common pattern of ORA We should check the spelling once again, then correct the identifier. How could this happen? All you need to know is that how to use exact form to express columns in SQL statements.
To use exact form of identifiers, we have to use double quotes to wrap column names, which notify the database to create the exact name as we provided. How exactly? At least, we should treat them as case-sensitive identifiers. From now on, we can no longer use the table loosely like the old days. Otherwise, we have great chances to use incorrect identifiers in statements and get ORA thereafter. Even though the column names are apparently the same as their definition, we still got ORA due to missing doubles quotes on columns.
Therefore, SQL parser cannot find a matched identifier in the table. Eventually, it raised ORA to alert the false column. The cure is simple, we should quote them exactly as we provided at the table creation, instead of non-quoted form. We used the exact form to make statements valid. As we can see, using exact form is very inconvenient, we should take care of every tiny detail on identifiers to prevent them from being invalidated.
It's worth noting that the exact form allows us to create columns filled with blanks, which are valid without ORA invalidation problem.
Let's see a normal table first. As we can see, I used one blank space for the third column and two blank spaces for the fourth column, they can work well without ORA as long as you follow the rule to query the table.
Any name collision or invalidation? No, this is because one blank is different from two blanks within the namespace of the same table, especially when we are using exact form to define the columns.
Even though we did not get any ORA and invalidation problem as we used the table carefully and properly, the exact-styled naming is really confusing. Try to describe the odd but valid table:. Consequently, it displays little information on the third and fourth column. For a new member, who has absolutely no idea what's going on here. Moreover, once ORA is thrown when querying such an odd table, no one is able to troubleshoot it.
This remind me that I had ever tried to remove a file with empty or blank name in an Unix OS. It took me a long time to fix it. So it unqualified the alias name by throwing ORA to alert the problem. Of course, you can use real column names to suppress ORA anytime.
The statements would be more stable in this way. That is to say, if you insist to use column aliases, an outer SELECT is your solution to ORA in this error pattern, which can regard all of your column aliases as real column names. Errors like ORA could happen in all kinds of object creation. Let's see some wrong types of identifiers to clarify the naming rules. Using reserved words are wild, everything that involves them may become unpredictable and nasty eventually.
You should never use them to name your database objects. Chances are, your users might create such database objects under totally unconscious situations. This is because their tools take care of the rest. It most happens because of the syntax issue. We have to be very careful with the syntax. The key is to remember syntax and write the code correctly. Reference: Oracle documentation. One of the most common cause of this error ORA invalid identifier means the column name entered is either missing or invalid.
It also Some time comes when you used reserved word in Oracle database. The following words are reserved by Oracle.
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