The problem of writing a compound SQL query

Scenario: I want to take data from n tables together, and then sort them in reverse chronological order. (User Dynamics)

Table 1 Co:cid name LinkId type date content

Table 2 To:tid name date title content

Table 3 Wowid name date title content

The LinkId in table 1 may be tid or wid, as determined by type.

Excuse me, how do you write such a statement? PS: It is better to take into account the efficiency problem ... I used a union to write one, the efficiency of the odd difference ...

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Scenario: I want to take data from n tables together, and then sort them in reverse chronological order. (User Dynamics)

Table 1 Co:cid name LinkId type date content

Table 2 To:tid name date title content

Table 3 Wowid name date title content

The LinkId in table 1 may be tid or wid, as determined by type.

Excuse me, how do you write such a statement? PS: It is better to take into account the efficiency problem ... I used a union to write one, the efficiency of the odd difference ...

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