diff --git a/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb b/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
index c32475c683..3756f74c95 100644
--- a/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
@@ -22,7 +22,7 @@ class Mysql2CaseSensitivityTest < ActiveRecord::Mysql2TestCase
     CollationTest.validates_uniqueness_of(:string_ci_column, case_sensitive: false)
     CollationTest.create!(string_ci_column: "A")
     invalid = CollationTest.new(string_ci_column: "a")
-    queries = assert_sql { invalid.save }
+    queries = capture_sql { invalid.save }
     ci_uniqueness_query = queries.detect { |q| q.match(/string_ci_column/) }
     assert_no_match(/lower/i, ci_uniqueness_query)
   end
@@ -31,7 +31,7 @@ class Mysql2CaseSensitivityTest < ActiveRecord::Mysql2TestCase
     CollationTest.validates_uniqueness_of(:string_cs_column, case_sensitive: false)
     CollationTest.create!(string_cs_column: "A")
     invalid = CollationTest.new(string_cs_column: "a")
-    queries = assert_sql { invalid.save }
+    queries = capture_sql { invalid.save }
     cs_uniqueness_query = queries.detect { |q| q.match(/string_cs_column/) }
     assert_match(/lower/i, cs_uniqueness_query)
   end
@@ -40,7 +40,7 @@ class Mysql2CaseSensitivityTest < ActiveRecord::Mysql2TestCase
     CollationTest.validates_uniqueness_of(:string_ci_column, case_sensitive: true)
     CollationTest.create!(string_ci_column: "A")
     invalid = CollationTest.new(string_ci_column: "A")
-    queries = assert_sql { invalid.save }
+    queries = capture_sql { invalid.save }
     ci_uniqueness_query = queries.detect { |q| q.match(/string_ci_column/) }
     assert_match(/binary/i, ci_uniqueness_query)
   end
@@ -49,7 +49,7 @@ class Mysql2CaseSensitivityTest < ActiveRecord::Mysql2TestCase
     CollationTest.validates_uniqueness_of(:string_cs_column, case_sensitive: true)
     CollationTest.create!(string_cs_column: "A")
     invalid = CollationTest.new(string_cs_column: "A")
-    queries = assert_sql { invalid.save }
+    queries = capture_sql { invalid.save }
     cs_uniqueness_query = queries.detect { |q| q.match(/string_cs_column/) }
     assert_no_match(/binary/i, cs_uniqueness_query)
   end
@@ -58,7 +58,7 @@ class Mysql2CaseSensitivityTest < ActiveRecord::Mysql2TestCase
     CollationTest.validates_uniqueness_of(:binary_column, case_sensitive: true)
     CollationTest.create!(binary_column: "A")
     invalid = CollationTest.new(binary_column: "A")
-    queries = assert_sql { invalid.save }
+    queries = capture_sql { invalid.save }
     bin_uniqueness_query = queries.detect { |q| q.match(/binary_column/) }
     assert_no_match(/\bBINARY\b/, bin_uniqueness_query)
   end
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index 33475e2e09..0d13174e12 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -185,7 +185,7 @@ class CalculationsTest < ActiveRecord::TestCase
   def test_limit_is_kept
     return if current_adapter?(:OracleAdapter)
 
-    queries = assert_sql { Account.limit(1).count }
+    queries = capture_sql { Account.limit(1).count }
     assert_equal 1, queries.length
     assert_match(/LIMIT/, queries.first)
   end
@@ -193,7 +193,7 @@ class CalculationsTest < ActiveRecord::TestCase
   def test_offset_is_kept
     return if current_adapter?(:OracleAdapter)
 
-    queries = assert_sql { Account.offset(1).count }
+    queries = capture_sql { Account.offset(1).count }
     assert_equal 1, queries.length
     assert_match(/OFFSET/, queries.first)
   end
@@ -201,14 +201,14 @@ class CalculationsTest < ActiveRecord::TestCase
   def test_limit_with_offset_is_kept
     return if current_adapter?(:OracleAdapter)
 
-    queries = assert_sql { Account.limit(1).offset(1).count }
+    queries = capture_sql { Account.limit(1).offset(1).count }
     assert_equal 1, queries.length
     assert_match(/LIMIT/, queries.first)
     assert_match(/OFFSET/, queries.first)
   end
 
   def test_no_limit_no_offset
-    queries = assert_sql { Account.count }
+    queries = capture_sql { Account.count }
     assert_equal 1, queries.length
     assert_no_match(/LIMIT/, queries.first)
     assert_no_match(/OFFSET/, queries.first)
@@ -224,15 +224,12 @@ class CalculationsTest < ActiveRecord::TestCase
   end
 
   def test_apply_distinct_in_count
-    queries = assert_sql do
+    queries = capture_sql do
       Account.distinct.count
       Account.group(:firm_id).distinct.count
     end
 
     queries.each do |query|
-      # `table_alias_length` in `column_alias_for` would execute
-      # "SHOW max_identifier_length" statement in PostgreSQL adapter.
-      next if query == "SHOW max_identifier_length"
       assert_match %r{\ASELECT(?! DISTINCT) COUNT\(DISTINCT\b}, query
     end
   end
@@ -464,7 +461,7 @@ class CalculationsTest < ActiveRecord::TestCase
 
   def test_should_not_perform_joined_include_by_default
     assert_equal Account.count, Account.includes(:firm).count
-    queries = assert_sql { Account.includes(:firm).count }
+    queries = capture_sql { Account.includes(:firm).count }
     assert_no_match(/join/i, queries.last)
   end
 
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 2417775ef1..4ec695c4c6 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -706,7 +706,7 @@ class RelationTest < ActiveRecord::TestCase
   end
 
   def test_to_sql_on_eager_join
-    expected = assert_sql {
+    expected = capture_sql {
       Post.eager_load(:last_comment).order("comments.id DESC").to_a
     }.first
     actual = Post.eager_load(:last_comment).order("comments.id DESC").to_sql